Children of Earth remains, for me, one of the best things I've ever seen on TV. I agree it's the Crowning Jewel of the Who Universe thus far. Critics love the thing... if you guys read Androzani's reviews, those girls HATE Torchwood most of the time, yet love COE. Just goes to show.
Thing is, COE showed us what Torchwood, and RTD, really were capable of. Torchwood was supposed to be this dark adult drama, tackling intense issues that Doctor Who could never go near while keeping in the same Universe. In series 1, it never quite did that. It was like RTD went a bit off the walls, thinking that what constitutes as an adult drama was sex, blood, guts, swearing and more sex. Oh, and an opportunity to show a gay relationship. Ianto and Jack in series 1 is, frankly, a fricking terrible coupling. The ONLY reason I can see them putting them together is to have a gay couple in the show. A gritty revenge plot with Ianto betraying the team was ultimately shoved aside. Terrible writing. It says a lot that Doctor Who series 3 tackled more dark adult issues than it's so called grown up counterpart, and did it superbly; two men who've lost their home (the Doctor and the Master), a woman who loves a man who'll never love her back etc.
It improved a bit in series 2; they toned down the juvenile stuff and actually pulled out of the bag some solid episodes. But it still wasn't really anything special; I watched it because it had Jack and was set in the Who Universe, and I wanted to be up to date with it when the rumours of the Uber Doctor Who series 4 final began to surface on the internet (the reason I first joined Digital Spy!), promising the Torchwood team would be in it, along with Sarah-Jane and her team! The character arc for Owen was just... weird. Brilliant idea, forgotten about and kind of abandoned. Toshiko's death was sad, but also seemed like a waste. Ianto and Jack continued to make no sense, and was shoved even more into the limelight. "Look, a gay couple! Look at us! LOOK!"
Children Of Earth, for me, was everything Torchwood could have been, and if RTD was to ever write his masterpiece, this would be it. It takes everything, EVERYTHING wrong with series 1 and 2 and turns it on its head. Ianto and Jack, for example, work here so beautifully because they finally delve into Ianto's character, showing him with his family and explaining that he's fascinated by Jack, but is conflicted over the mysteries around him. Jack, for his part, cares for Ianto, but I do feel he doesn't realize just how much until it's too late. It's what makes his death all the more sad, and it's a superbly written relationship. RTD doesn't put a foot wrong here, and it does redeem how rubbish it was at the start.
I agree with above posters; Jack marching in to confront the 456 was definitely supposed to be a way of reminding us Jack's not the Doctor. This is a very intense, dark and, at times, hard to watch five episodes of TV, and you could be forgiven for forgetting that it's set in the Doctor Who universe. But, a running theme throughout is that the Doctor does not show up to save the day. Things go from bad, to worse, to worse still, and still he does not come. Jack, always full of confidence, thinks that, today, he has to be the Doctor, but, of course, the Doctor he is not, and this leads to the death of his lover.
What I love about COE most of all is that you can take the Who Universe completely out of the equation and it's still a superb piece of TV. It's main theme is the depths humanity will sink to to survive. That it will happily sacrifice thousands of children to save itself. The villains here are the humans, and while Jack does beat the 456 in the end, you aren't left cheering him on. If anything, you're left cold, and a little appalled. A series that can make you think about it for weeks after is a success.
Which is why it breaks my heart that Miracle Day even exists. Everything COE fixed about Torchwood, everything it did to make it go from an OK show to a superb one, is thrown out of the window. Miracle Day ranged from OK, to bland, to God awful television. RTD and the writing team in general could have done so much better. I agree with an above poster; I like to pretend it never happened. There's no way MD occurred in a Universe with the Doctor in it. No way. What makes COE make so much sense is that it's over in 5 days. The Doctor only comes by now and again. Miracle Day takes place over months, in a time we know the Doctor was around. Maybe he was ignoring calls from the Ponds at the time, but no way in hell would he ignore:
"Doctor! It's Martha! Remember me! The woman who saved your arse a few years back, going on the run for a year... etc? Well, urm, you know that Planet you're obsessed with? Well, nobody's dying! Like, nobody! We dunno what's going on! Doctor, we need you!"
Or maybe he did. Who knows?