I'm very happy with my new camera and I don't regret going with Pentax. I can't really do a review because I'm still learning how to use the d-slr (I wasn't even using AF when I was shooting film).
I'm very impressed with the noise when shooting at 1600ISO which was something that worried me (from what I saw in some digital P+S). In the K10D it's very soft and appealing to me.
The DA*50-135 f2.8 is a fabulous lens as well. Once you update the firmware (v.1.30), it's almost silent! It really makes a difference. I think it's pretty quick but as I've said I never really used AF before.
The images are quite crisp and it works wonders even in very dark situations. If you look in my photo gallery (I'm also learning how to use Aperture), the first 3 images were taken in a room where the shutters we closed "à l'espagnol" so there was very little natural light coming into the room.
Many reviews state that the K10D is very heavy so I suppose I was expecting a beast. Not so! Everything is relative of course. Compared to my Nikon F90x, the K10D is lightweight! ^.^ Of course when you attach the 50-135 it's much heavier but again, I was expecting much worse. I do notice though that I tend to tilt to the left so perhaps I really should consider buying a monopod for when I go outside.
I'm still in the learning process concerning the different exposure modes so it would be unfair for me to say anything about them. Overall, I've been happy with the exposure metering (especially since I've been shooting in darkish environment).