I've never thought of myself as tall, but based on the responses here I must be a giant. I'm 5'4", and I absolutely adore my 29er.
My standover clearance is the same (more actually) than my last 26" MTB, and the overall fit is better too. Of course that just points to a poor fit on my first bike, and isn't a statement on 26" bikes in general. But at 5'4" I was able to comfortably fit on, and test-ride, several 29ers. I think 5'3" / 5'4" is about the limit though to comfortably fit on a 29er.
From the moment I got on my 29er I felt more comfortable and confident. I love the way it handles, and I saw an immediate gain in my riding. In fact I didn't really start riding consistently until I got my Niner. Now I'm so in love with it I ride 3 - 4 days a week.
I do have one criticism though. It's mostly me, really, but due to my lack of strength (I'm still building my base) and a bad knee the gearing was too high. The crankset on a 29er is the same as on your 26" bike, but the wheels are bigger. So effectively your gearing is higher, and I lost my really low gears for the long steep climbs. We tried replacing the small 22 tooth ring with a smaller 20 tooth ring, but kept having problems with the chain. Turned out the chain was hitting the part of the crank that houses the bolts. We were able to fix it by shaving down those knobs, so I've got all the gears I want, but if you're a slow climber like me it's a consideration.

