I have had mine for almost 2 years I think, although it looks like I've had it for 20. Still works like clockwork though.
I shoot raw mostly, and I can't say I've noticed mine underexposing - or at least I am happy with the way it exposes. A slightly dark picture can be corrected in post much more readily than can a blown one, so I'm happy.
I used ISO 6400 the other day for the first time, and that was poor - worse than a modern phone levels of bad. Most of the time I rarely go above ISO 800, although I give it leeway to go up to 1600 if needs must.
It's a good, solid camera. I'd love a K-5 for it's low noise (and the astro-tracking GPS thing) but for as long as the K7 still works it's camera enough for me, and I'll spend whatever spare cash I can afford on glass instead. Hopefully by the time the k7 dies I will be able to get a bargain k5 or better.
I do hope Pentax keep this basic body shape too; it works well, and it means there is a chance I might be able to hire a waterproof housing one day