I currently have the game on steam, I'd recommend that you not buy it unless you really want it. From when I played it last (About a year ago) it was alright but it can be completed in a matter of (I'm not sure of the exact time but about 3 hrs); After a certain point you can pretty much leave the game to play itself and I found even with the other game modes it didn't have much re-play-ability.
Edit: I can't remember the game very well so don't base all of your info off of my info =P