The Mongoose Blackcomb is the best bike I have ever owned in my short life, but other people that are whiny would say different. To me the weight is not bad at all, because I just bike around like 10-20 miles each time I ride (on/off road), but if your going to ride like 50-70 miles a day (if so you probably already have a good bike) do not pick this one.
Very good deal for the money, but make sure you check all the parts to make sure it is assembled correctly, because when Walmart puts them together, they are just slapping them together, they don't care if anyone gets hurt. (Mean to say, but usually true.)
Nice suspension in the front and rear, both adjustable. This bike also has disc brakes in the front and back for superior stopping power! Several bad things include: the brake pads wear out fast, the derailleurs are hard to adjust perfect, the seat is somewhat uncofortable (but would be easily replacable for cheap), and the place where you put a bottle holder is angled funny so if you hit a big bump that bottle will fall out, so make sure you get one you can put some where else, or put a rubber band around it, but that depends on the shape of you water bottle I guess.
I would recommend this bike to someone who wants a tough, nice bike.