Okay, I posted this review on play.com (it's not been published yet) of Children of Earth and thought that maybe you'd like to read it *shrugs*. I've tried to keep it honest and put some positives in there (okay, I managed one) and also tried to keep it impartial. Note the 'tried' part of that sentence.
Anyways, here goes:
Okay, I was really excited by the release of this third series, and got nothing but five days of disappointment. The entire thing felt strange within the Torchwood canon, and if anything the plot was written first, and then Torchwood was shoe-horned in later. I mean: what did Torchwood actually do? They spent most of the time in a warehouse watching a video feed - and when they did get involved, they made themselves look like complete idiots and got one of their team (the only one left that was likable after what they did to Captain Jack this series and the way Gwen was written pretty much throughout the show) killed!
You watch this expecting a good, science-fiction adventure and what you get is a melodramatic political drama with an alien in a tank that likes to screech a lot, with a touch of Torchwood thrown in as a vehicle to get people to care about the story. They do show us some background on Jack and Ianto, though all we really learn is that Jack is a heartless git (I believe they used the phrase "serious character development" to explain this) and we all have the rug pulled out from under our feet when we discover everything we've learnt about Ianto so far is a complete lie and no one knew him at all.
To be honest, I'm not sure what 'Children of Earth' was really trying to tell us. You get a bit of "drugs are bad" mixed with "politicians are just as bad" and there's even the feeling that "everything you ever love will either leave you or die as a result of your own actions". Add in to the mix that they branded Ianto Jones with a lambda (an international symbol of gay pride) on his cheek, the suggestion that homosexuality has its own unique scent and Jack being uncharacteristically bastardish to the man he apparently loves before carelessly getting him killed by a mysterious and incurable virus, and you can't help but wonder if there's an underlying theme of "don't be gay - you'll end up being killed by a terrible illness and no one will love you". I don't care if Russell T. Davies is gay, he can't get away with that kind of thing on a 'double standards' card.
The plot holes are massive and infuriating - with viruses released from air tight tanks and the apparent ability for childrens' voices to travel in space (that's right - apparently sound can move through space!) as well as vast continuity, science and what I can only describe as 'common sense' errors and it's almost like they didn't really think this Amazing Piece of Television through at all. The underlying themes of sacrifice are totally cancelled out by the fact that, once again, PC Gwen Cooper remains pretty much untouched by the entire proceedings and a lot of the plot loses credibility for the mere fact she's becoming - in the words of the fans - a 'Mary Sue'. You can't help but agree. She doesn't so much as break a nail or scuff her expensive boots throughout the entire thing, and it jars the story - especially when other characters have been killed off with almost gleeful abandon.
There is also the issue of where Torchwood was at when the series ended: basically, they were no where. Gwen is pregnant (somehow, she managed to acquire a womb of steel and not miscarry during the emotional and physical trauma of 'Children of Earth'), Jack is completely broken and back to where he started from before he met the Doctor; Ianto, Tosh and Owen are all dead within five episodes and lord knows who the new team is going to be. Lois was very nervous and bumbling; Johnson was far too trigger happy. While Jack has his moments, at least he goes for kneecaps rather than brains.
So yes: You'll probably like this if you're a fan of Gwen Cooper, hate gays - or maybe just don't mind lazy, sloppy writing.