It's possibly this difference in my viewing approach that leads my opinion of it to be decidedly more mixed than that of the general population.
Certainly, Torchwood suits the longer episodes, shorter season episodic plot approach much better than the self-contained 45 minute stories that it was dealing with in Seasons One and Two. (The contraint to 45 minutes is also, arguably, a restrictive effect on Doctor Who as well.)
And, indeed, the benefit of the BBCOne slot is very obvious - the quality of the "non-Torchwood" actors was significant, with the kind of names you simply can't get to appear in things on BBC Two or Three. But this was also a negative, in a way, since actors like Peter Capaldi made the "regulars", especially John Barrowman (who has always been an actor more suited to Broadway than Television), look stilted and amateur by comparison. Indeed, one has to approach the unwelcome argument that the only way to improve the series would have been to ditch Torchwood itself.
This also extends to the plot construction. The most compelling sections of the plot were the directly political ones, Capaldi's civil servant making increasingly damning decisions for the ministers who wished to avoid their own culpability, the (standard RTD) cynical view of the machinations of governments themselves; and the "pure SF" ones, with the fairly impressive alienness of the 456, and the "anti-Q", Mr Decker, who appears to have been the Government's man on aliens since the 1960s.
In comparison, the Torchwood plot was hamstrung by having to, perversely, avoid the more fantastical elements of the organisation in order to spent all of their credits in "suspension of disbelief" on Captain Jack's immortality. In response, Torchwood, and Jack's, effectiveness is progressively compromised narratively, in a manner which almost looks like RTD is trying to destroy the show so that no-one else can use it (although, placing Jack in a position where he can potentially guest in Doctor Who if Moffat wants to use him).
Indeed, I was starting to be generally fairly impressed with things, (despite the above issues, and niggling problems with the handgun fetishism* that RTD seems to have, and the composition of the 456 breathing mix (which is so chemically unstable that I suspect you'd need big circulating pumps constantly renewing it to keep it in the right composition)), until the "revelation" of the 456's true needs.
The (spoilery) Bad
Which is where it all falls apart for me. RTD has a perverse liking for twisting plot and logic around in the service of some kind of political or moral point, and I was disappointed to find a great example of such here.
It turns out, you see, that the 456 want human children so that they can surgically attach them to themselves (don't ask how the child survives in 11% fluorine atmosphere with only a gas mask), for the hit, and that, in the words of the Token Black American General** "Britain started this trade in the 1960s" and complains at the results.
Nothing like the situation in Afghanistan, then, Russell. Or China, or South America. No, nothing like that at all.
The problem is that this rationale for the 456's actions makes no real sense. They say that human children produce "chemicals" that they enjoy, but demonstrate repeatedly that they are a culture of vast biochemical sophistication. If they can make a virus capable of killing humans in minutes (and that's probably almost impossible, given viral replication rates - you'd be better off with a simpler poison, like, oo, hydrogen cyanide), then it seems odd that they can't engineer something to give them a more effective hit than a whole child, especially when it would be easier than going and getting humanity to round them up for them.
(In fact, this is what happens to drugs in the Real World - few people still chew coca leaves for the high when they can use the more concentrated (and less frangible) pure product, cocaine. And LSD, MDMA and many other modern drugs are purely artificial and easily produced from chemical precursors (in fact, even cocaine can be synthesised, but it is cheaper to harvest the crop in bulk.).)
Even if, for some reason, the 456 are culturally opposed to synthetic drugs, one wonders why they want to take a limited number of children when it would be much more effective to demand a breeding population of adults to create their own self-sustaining source of children. Humans are very good at reproducing, so this wouldn't be a significant problem for them, if they'd started in 1965 with a seed population of 100 or so.
None of these things were a problem before the analogy was made - and indeed, none of these are objections to the Season One episode "Small Worlds" which contains a similarish plotline (children taken by unbeatably superior beings (fairies, in this case)), even to the extent of a B-plot about an aged relative of Jack's, torn by his continued youth. (Of course, in "Small Worlds", Torchwood loses, so...)
(A lesser point about RTD's disappointing tendencies to the obvious in this regard; the self-serving PM is called "Mr Green". I am looking away from you in shame, Mr Davies, in shame.)
The Series of Which We Shall Not Name
Speaking of looking away from people in shame, I notice that The Doctor has now completed his transformation in Messiah to the extent that people are encountering the Problem of Evil when discussing him. The Doctor, and Doctor Who in general, has always been a problem for Torchwood - RTD has admitted that he finds it difficult to write Torchwood and Doctor Who in the same consistent universe (and copped-out with the season ender for New Who, "The Stolen Earth"/"Journey's End", locking all but Jack in plot-induced time freeze for the storyline), and seems to have resolved this by elevating The Doctor to a position of god-like goodness, a man (admittedly, in a description presumably due to Jack) or being who exists purely to save the Earth from its problems, and forgive our sins (he even died for them, just like Jack did in Season One - they both got better). Considering RTD's tendency to deconstruct his heroes - Jack comes off badly in Torchwood, but The Doctor comes of as badly by the end of New Who in his own eyes - one does feel that he's taking the chance to indulge himself here with the one character he can never use in Torchwood at all.
And, the other character he couldn't use because her actress decided to be in The Bill, Martha Jones, is both written out in a single line (on her honeymoon), and replaced with... a plucky young black woman, who even wears the same Torchwood issue contact-lenses that Martha did in her first Torchwood appearance.
Anyone can be replaced, eh, Russell?
(Of course, remember that All Of This is The Doctor's fault - he destroyed Harriet Jones in a fit of pique, removing the Glorious Period of British Government from history, and letting "Mr Green" in in her place (after a certain John Saxon was dealt with). The Doctor, who "looks away in shame at what humanity does", is actually indirectly responsible for all of this.
The Ugly SPOILERS
But, of course, it isn't "what humanity does" at all. The only people who perform morally dubious acts are individuals in positions of (elected or unelected) power - the Cabinet, the PM, highly placed civil servants, and Torchwood themselves. "The people" are kind, if simple and a little bigoted in a humorous way, folk, who could never be told the truth about the 456's need for 10% of the children of the Earth because they'd riot.
Jack tells us this, and we are shown this in all the Cardiff scenes, with the cuddly thuggish estate kids in surprisingly nice clothes, and the cuddly thuggish lads who romantically (and surprisingly successfully) mob the
It's just a pity that it isn't true. Note that Africa is never really mentioned in the serial at all, and Asia barely so. One feels that the Chinese government (for example) would have little problems disposing of 10% of its children - indeed, one wonders if they'd feel like gaining extra credit for giving the 456 an additional bonus. And there are many countries with cultural positions that would make it quite easy to find children that the majority wouldn't really care about. Even the "civilised West" has felt this way about many sections of society relatively recently (and still does - the nod at the "Failed Asylum Seekers" list is sadly underplayed), and one feels that it would be quite easy to get the population of the world to pick people to discriminate against to save their own skins.
And, indeed, I may be alone in this, but it appears that the position that 10% of the world's children for us not being wiped out is a pretty good deal is considered untenable. Jack is morally compromised for us by even his willingness to sacrifice one child to save the world, and Gwen is unambiguously (except for a brief, token, dark(ish) evening of the soul) happy about being pregnant (although she was taking the Pill, and presumably is aware that she's in quite a dangerous line of work - and was traumatised by a parasitic alien baby pregnancy recently).
Apparently, children are so important, that their moral value is infinite. It's a curiously Daily Mailish philosophical position for Torchwood to adopt, not even really a humanist position, but a knee-jerk reaction to a modern perspective on children born of the conditions of the West in the last 100 years.
The Summing Up SPOILERS
Overall, Torchwood: CoE was above average up until the final two episodes. Its still clear that RTD wanted to kill off "his" show - poor Ianto dying due to the Jack's apparent total lack of any consideration of the consequences of basically telling sufficiently advanced aliens to fuck off (even though Mr Decker managed to survive the same circumstances, dodging an ironic death because the plot needed him as a tempting serpent in the final act), Jack fleeing his conscience only to become a giant head in a jar in the future, and Gwen presumably off active duty heavily pregnant.
The plus side, of course, being that if they bring Torchwood back, they'll have to make it about Torchwood Two, the barely mentioned Glasgow unit run by a "very strange man" (although, it is mentioned in CoE that Torchwood Two has been disbanded, presumably to avoid people like me nitpicking about the lack of said man in the serial...).
To crassly summarize in numbers: 7/10, (8/10 until the bloody allegory).
*Every time someone is shot, once, in the body with a semiautomatic pistol, they fall over dead, instantly. Big soldier guys with machine guns and automatic rifles fail to even hit anyone, even at relatively close range, or with sights. In TV Tropes terms, this is a combination of the Instant Death Bullet and Improbable Aiming Skills tropes, although all the automatic weapons, and some of the handguns, also feature Hollywood Silencers.
**Who shares his militariness with the Token British/UNIT Black General, the only other significant black male in the series. One wonders if RTD thinks that all important military men look like Colin Powell...