Well I have to say after having my H3 for 2 years now (and 40k+ miles) it's a better overall vehicle than my wife's JK, my old XJ, and my old Suburban. I've pretty much already decided I'll be one of the first in line for the H3T (and wifeys already said yes!).
Why? Well first and foremost it's a great balance between daily driver and offroad capability. Very comfortable seats for long drives, out-of-the-box more capable than just about anything but a Rubi, nice (for stock) stereo, decent interior room for a mid-size truck. I put 100k miles on my XJ (lifted, 33" tires, etc) and it wasn't even close - I'll take my H3 in a heartbeat! Yeah, visibility sucks, it doesn't go fast (neither does the JK or my XJ or the Suburban), and gets crappy gas mileage(of course, it does get better gas mileage than any other 4wd vehicle I've ever owned (average hiway is around 18-19 w/o roof rack, a little less than the JK and waaay better than my XJs 14-15 and the Subs 12).
Oh yeah, Hummers also use GM's 'uptier' warranty service, same as Caddy's. That means free tow from wherever (including offroad situations), free rental, etc. So the 2 times I've had the H3 in the shop (airbag light from unplugged sensor and dead battery) I've had fantastic service, free tow, free rental, wifi in the service area, free cookies, and the best customer service I've ever had with a new car. Some of that is the dealer, but Hummer places a huge premium on customer service you will not get buying a regular GM car (or yota, nissan, etc)
Would I take it on a worldwide expedition? Not likely, too hard to find parts, and too much risk of it getting stolen (gotta admit Hummers are sexy targets). There's also some questions about reliability of the front aluminum difs (they are CI on the Alphas). Only reason I'm gonna get the truck is my wife's allergic to the dogs and we need to put them outside, otherwise I'd keep my H3 for another few years.
I see so many people complain about the power/visibility, and yes, they are a pain, but you get used to those couple quirks and the other benefits make it well worth having as a DD/Offroad rig.