If it's your first MTB, I'd say it's a good deal. Really depends on what type of riding you will be doing. A new one with that level of components would be twice that.
After purchase, if you don't know much about working on a bike, I'd take it in to your local bike shop to have them go over the bike/tuneup.
As far as reliable, it all comes down to the parts. It's a MTB and you will be replacing parts more often than a road bike due to dirt and mud.
Good luck.