Now that I have had the 29er for a couple of weeks and had a good few rides on different trails it's time for some initial feedback.
You get nothing in this world for free. The greater inertia of the larger wheel is noticeable quite often. When pulling off from a standing start and cornering it is a negative. It simply does not change direction as quickly as a comparable 26er and it is slower to pull away. However, when hitting obstacles at slowish speeds when a 26er might stall, the extra inertia helps carry you through. It could also be down to the bigger roll and I think these both combine to give the smooth ride that it gives. It really does smooth out some trails that are real filling rattlers on my modern hardtail. It also covers this ground a lot faster, whether that is inertia, roll or comfort or a combination of the three. The rest of the time I have not found it to be noticeable.
There are some trail obstacles that even a 29er can't overcome. It is not a wonder bike and lack of speed, skill or both will still stop you. And while it's smooth riding, a rooty descent with rigid forks is still punishing.
What Kaiser said about being more 'in' the bike is true. I have noticed especially when out of the saddle that I don't dominate the bike so much, which is a good thing. I think I feel more like a kid on this bike.
Since I got the monkey I have only ridden a 26er once, and while I think other factors were involved, I didn't enjoy the ride. The next night the monkey was back out.
It's far too soon for me to be making proclamations about the future of mountain biking, but I am really enjoying my 29er experience so far and I'm glad I have one in my stable.