I love my K10, but it's been used somewhat rarely over the last couple of years in favor of laziness and power zoom P&S. The problem I have with my K10 is the noisy high iso images, the focus hunting with indoor shots, and a few other things. So in the resent past, I end up just grabbing my G1x or other P&S camera. A short time back I got a K5IIs for under $500. and I'm pleased to say that I'm into my SLR again. Just this morning I was looking for some pics from a few years back, and I came across a session of K10/Sigma 18~50 shots, and I was taken aback of the IQ I found.
In all fairness I'd need to do the same sort of shoot with the same lens on my IIs, as to get an absolute opinion, but for now I'd be dishonest if I were to say the K5IIs looks better.
First thing that popped into my head was Kodachrome, as I gazed at these K10 pics. I then pulled up some K5 pics from last week(same sort of stuff, outdoors flowers), and the thing that popped into my head was sort of bland $3. walmart film look.
Don't get me wrong! The K5IIs is a better camera in almost every way. But at iso 100 in daylight, the k10 is very hard to beat! Also I'm sure a lot of the IQ can be brought back in PP, but some of it can't, like the creamy looking to of focus areas of the K10. There sooooooo rich, it reminds me of my pics with Kodachrome and my Contax RTSII. I just don't see it with my K5IIs. What I do get with my K5 is no more highlight clipping(thats so nice).
But I love both camera's, and I'm glad I waited as long as I did for a K10 replacement.
Pics from K10D