My take:
I think what we're seeing here is history repeating itself.
In 1981, Tom Baker was still everyone's favorite Doctor ever. I suspect that the announcement that Peter Davison would be coming on rather disappointed a lot of people and/or left them skeptical. However, I think Davison's turn as the Doctor is an excellent one. (Yes, Adric sucks, and the other companions were a bit irritating, but Davison was a good doctor.)
Fast forward to 2010. Tennant is everyone's favorite Doctor currently, and the new guy (Smith) is looked on with suspicion and skepticism. Totally reasonable, but just bear in mind he could end up being pretty good. I'm definitely picking up on the "old man in a young body" thing, and I think his costume style really reflects that. He's not an emo doctor, he's more sort of a schoolteacher (at least from the look).
As far as the teaser itself...eh. Nothin' special. Daleks are back (what a stunner...), weeping angels, too.
I do agree that the whole mooney-eyed "oooh Doctor, I luuuurv you" thing needs to go, but I'm hopeful they'll keep that to a minimum. I hope they don't go in the opposite direction, too (a la Peri and 6 at the beginning of their run...).
The only thing that makes me wary is some of the facial expressions in the teaser. They looked a bit.....goofy. I hope that doesn't mean the show is trying to skew younger.