The K10d was a GREAT first dSLR. Easy enough for a beginner but super feature rich to grow into. I got gorgeous pics from that cam. But after a while, I started noticing vertical banding in dark high ISO shots (800+). And then I started getting back-focusing issues. And apparently, the first batch of K10's to hit the market were riddled with these problems (and updated firmware didn't fix it). You can do a search for 'VPN' and 'back-focus' and K10d on the Pentax SLR dpreview board and find alllll kinds of posts.
I called Pentax to get my cam serviced (it was out of warranty at that point). They said that since I use a 'non-Pentax' lens as my main lens when experiencing the back-focusing problems, then they could NOT service my cam. They needed to calibrate both cam and lens together and since I used a Sigma lens, it was a no go.
The final clincher was: I was absolutely honored to be asked to take pictures of a friend's mother who was literally in her final days dying from terminal cancer. I took the pictures in front of a beautiful bush and sure enough, almost ALL the pics were back-focused on the bush and the faces were blurry. I was livid. They looked fine on my LCD screen but the computer screen revealed all the subtle blurriness. That woman passed away a short time later and there weren't any more chances for a 'do over'.
I posted this issue on dpreview to get tips on what I could do remedy the problem. Some folks thought it was user error and NOT the cam's fault... other's chimed in that they were experiencing the same problems with their K10d's.
I said, to heck with all of it!! I'm getting a NIKON!
So here I am today with a D90 (almost got the D300 since it was more comparable to what I had but I wanted a LIGHTER dSLR this time). But even with Nikon, my first D90 from
Amazon I had to send back (long story). This new one seems to be working ok so far. I LOVE this cam. No more vertical banding and no more back focusing issues. However, I did experience the infamous 'ERROR' message on the lcd. Only happened once with this new body (happened LOTS with the first body). I think the D90's have a sensitive lens lock button... if touched in any way while shooting, it can give you an error message. If I reset the lens real quick, it goes away. And there other theories that there might be a memory card compatibility issue.
Moral of the story?? ALL dSLR's on the market today are HIGHLY capable cams. And EVERY manufacturer has it's own set of problems with almost every model. You just gotta pick one you think will serve your photography needs best and go with it!