29ers are for real! Especially around here. Sand? No problem. Roots? No problem. Uphills? No problem. Like was said above, it takes a bit longer to get the wheels moving, but they hold momentum very well. Its like cheating going down and up the drops because the bike just keeps moving.
I don't think I'll ever go back to 26" unless its a cheap bike build or jump bike or something like that.
If you're serious about them, you should look into one of the many rigid single speed 29'ers. You get good components and a very fun bike for the money. It really put the fun back into riding for me.