Perhaps I had lower expectations this week, but I enjoyed this a lot more than last week, the story pulled itself together quite well and most of the answers were satisfying enough, if not exactly unpredictable. Yes the little girl was CAL, yes it was the computer's own virtual world, yes the 4022 were "saved" to the hard drive etc. But the backstory of how CAL became CAL was a nice touch, and it was all quite well done.

Still not convinced that the "Vashta Nerada" are quite as clever an idea as all that, or that they were particularly well realised on screen. Yes, shadows can be scary, but what we had here wasn't shadows, but various skeletons in space suits (space suits being excellent protection against the vashta nerada of course, except for the fact that most of those in the space suits got eaten, while the bloke in the brown suit standing inches away was just fine). Also, the existence of River Song massively irritates me. Her story actually worked okay in these two episodes, but the problem is, she's now cast a shadow of her own upon the entirety of the rest of the show. You can't look at William Hartnell or Tom Baker now without knowing that one day, that character is going to be married to Moll Flanders, only of course it's so far in the future (and Alex Kingston is so definitely not coming back for it) we'll never see any of that happen anyway. It's a spoiler in the truest sense, and it bugs me.

Yes.

I'm convinced it's a gift to the fanfic authors.

If only there was some way to travel in time, and change the future by affecting the past. Some non-linear view of time we could take.

It would all be like a big wibbley, wobbly ball of time-y wime-y stuff.

Unfortunately if you try, a bunch of pterodactyls from the void will eat your face.

Unless they don't.