I have both, here's my take, all IMHO:
On the trail the 29er isn't as nimble when climbing slowly in rock gardens. On trails, the 29er's rear wheel climbs better when I sit and spin, rear wheel eats up all the bumps and stumps. On fast downhills with loose sand/gravel, the 29er is more stable.
On the roads, 29er handles better in all areas. Difference in wheel weigh is very subtle, larger wheel handles curbs and expansion joints much better. Better climbing out of the saddle. I'm not having any trouble with the stock gearing, 10" steps work well for me.
Is it worth the hype...maybe. IMHO, both sizes have their advantages and disadvantages. As a taller rider (6' 2") I'm sure 29er is better for me. Under ~5' 10" riders might want to be sure before they buy a 29er. Under 5' 6" riders, I wouldn't buy one.
This is my opinion, YMMV :thumbsup: