I think The Silence are definitely on a par with the Weeping Angels. I was only about 13 when they first featured in Blink and they scared the hell out of me.
I was a bit lost at the beginning, but then after he was killed I thought 'oh, so that how it happens' because some IDIOT told me a week beforehand that the Doctor died in the first episode.
I got a bit confused, which is a good thing. I can tell it's good writing if it's so complex that I can't quite understand it on the first time of watching.
There's supposedly some rumour that David Tennannt is coming back...but I'm guessing it's just my DT-mad friend getting excitable.
More than a rumour. In the pre-series trailer you can see a brief snippet of the old Tardis.