Just picked up a lightly used '12 Trek Marlin the other day to get back into biking. I used to ride a single track by my old highschool years ago but had stopped. Decided biking would be easier on my knees then running is and it is so far. We'll see once I start hitting the trails up again, only done some light trail riding the past couple days.
The only thing(s) I don't like about it so far is that the front brake sucks, it works but its not grabby enough for me. That and the pedals suck, my feet slide around every once in a while. Might have to swing by my LBS and check out some platform pedals.
http://img.photobucket.com/albums/v326/StevenCole/null-15.jpg