I do like the Doctor's trick to escape the angels. Unusually for Doctor Who, it actually makes a certain amount of physical sense too - assuming that some sort of artificial gravity generator could be made, it'd interact just fine with other gravitational fields.
Ah, now we have the crack for this pair of episodes, and this time the main characters have seen it. And it's bigger, which is never a good sign. And it's spewing out time energy, and eating the very existence of anything and everything that enters it. So presumably it's opened onto something really bad, unlike the first one which just opened onto a prison cell, and the next two which were just there.
Having Amy count down to her own demise is a rather sadistic touch of the angels, and also a great way to push the Doctor's beserk button. The angels seem determined to commit suicide by Doctor. Then again, most Doctor Who villains ultimately end up doing this.
Oh, and for anyone who didn't catch it: the date when the event that caused the cracks occurred/will occur/is occurring: 26-06-2010. That just happens to be the date when the final episode of this series (assuming 13 episode with no rescheduling) airs.