29ers have their pros and cons compared to a standard mtb with 26inch wheels. Greater rolling resistance and harder to get up to speed, but carry that speed really well. Harder to manage in the tight, twisty stuff, but smooths out the bumps better. There's enough of a market that most manufacturers are coming out with 29er versions of things like forks, wheels and tyres, but oddly enough, 29er tubes can be quite hard to come by. If you are quite short, a 29er probably just won't feel right, but if you are tall, it may just feel like a match made.

So, um, no easy answer, eh. Go ride some bikes.