I own that NEXT bike.. It's not a bike for serious riding.
The NEXT bike uses pretty low-end grip-twist shifters and derailleurs, it's also a heavy frame (the bike weighs around 40 pounds, surprisingly heavy for an aluminum frame), and the rear suspension spring is way too bouncy. I have the spring tension adjuster screwed to its tightest compression and it's still too mushy, which means when you pedal it will cause the suspension to flex a lot and absorb a lot of your pedaling power. That means you can't go very fast and you will get tired fast.
The wheels are also a bit flimsy.. After just a couple of rides the rims started getting kinks which will need truing to get straightened out. More expensive wheels such as the triple-laced wheels on high-end mountain bikes will hold their shape much better.
Also, the frame only comes in 1 size for that bike, which is the average size for men. It's probably too big for 80% of the female population IMHO. That means you will have to stretch to reach the handlebars and it might cause you lower back, arm and wrist discomfort.
I use that NEXT bike as my "beater" bike, which I ride short distances from home to run errands. It's such a cheap bike, I can leave it locked up against a signpost on the street and no thieves would bother to steal parts off of it. I also own a much better bike (Specialized Sirrus LTD) for long-distance recreational rides.
If you are looking for a bike to do more than just tooling around the neighborhood to run errands, I would advise you to go to a bike shop, get fitted for a proper frame size, then choose from the bike shop's selection of mountain bikes with the proper-size frame.