Yeah, as long as the fork isn't shot, I'd say $500 is a great deal. I have an 06 rockhopper (base) and it's a tank except for the fork, and the fork on the comp disc is considerable better.

It's a solid all-around bike. The only cons I can think of are that it's not ultra-light (i.e. it weighs in around 30lbs) if you're a racer/weight weenie type (not that there's anything wrong with that), and that the discs aren't hydraulic -- but depending on how that bike was spec'd (sometimes shops build them up with diff. brakes), it should be fine. BB5's (as per the website) are nice brakes, not as easily adjusted as BB7's, but still good for stopping.

Pros are: it's tough, it's not that heavy, so you can climb with it, and it's a solid go-almost-anywhere bike. Moderate drops (3' ish), trails, street (with lockout fork and some decent-rolling tires, I can cruise at 15-18 mph all day long on the road without much effort), you name it, this is a good bike.