Well, I've watched it twice, and I confess I find it hard to get as excited as everyone else. Libraries have been the setting for enough horror and drama that this was just one more (and a humano-centric one at that - books the size and shape for humans to read). Likewise the terror in the shadow. I'm sure I've read/seen something else with people having two shadows. I can't recall what - but it just didn't feel fresh. And there were too many other bits that were repeated ideas (the doctor talking in the TV? Don't blink!) Likewise the characters: the businessman more interested in his patents than people's lives, his dippy secretary, the staunch military type... never seen any of them before. And the zombie spacesuit - I so saw that coming. The 'zombie walk' was cliched.
I did like the idea of River Song - the idea that time travellers lines would cross and get tangled is very interesting. But I can't help feeling (sorry guys) that it would get old very quickly. Let her drop into the Doctor's timeline very, very sparingly, hinting at spoilers and disappearing, and she'll be very effective. I hope Moffat is able to see that - RTD would flog the idea to death. Oh, and we're talking more than 13 generations if he's currently 'very young'!
The child's environment was interesting too. Slightly surreal, strange mix of cultures and eras going on, even to a 60s cream phone. Felt a little like the bar in the last ep of Quantum Leap.
But unlike everyone else, I don't feel very 'cliff-hung'. The child is CAL, and her environment is a self-creation for sense of safety. It is her task to 'save' the people in the library - as she saved the 4000 odd who were there when it shut down: saved them to her 'extensive flesh banks', that is. She shut down the library, and now it has been 'breached' by more people.
The introduction of the 'data ghost' is to present the idea that consciousness can be preserved in data form, so that having been 'saved' it can also be restored at the end. Including, of course, Donna's data and consciousness.
I really hope I'm wrong, and it's not all that predictable. I want to be surprised.