I have been climbing at NCC for about a year and a half, and have thoroughly enjoyed my time climbing there.  It's not the prettiest gym, but the people are friendly and the routes are good and constantly changing.  Since the new management has taken over, this place has only been improving - the only downside, it's become much more crowded, typically with birthday parties full of kids.  The staff is friendly, laid back, and very helpful, and happy to give advice to climbers of all skill levels.  The laid back attitude can sometimes backfire when little kids or soccer moms with video cameras walk infront of you while you're in the middle of a boulder problem, but the problem is not that common (yet frustrating when it happens).  But all-in-all, if you're on the south side of Vegas, this is your place to climb if you want to climb in a gym.