I think there might be some other discussion on the forums about it, but here's my 2 cents (after owning an H3 for 2 years and seriously asking myself that question)
Pros: Very nice ride, comfortable interior, well laid out. Lots of dash space for accessories, plenty of useable connections in the fuse box. Parts available at any GM dealer (orderable, not necessarily in-stock). Very capable off-road out-of-the box. Can fit 35" tires stock, get the adventure package and you get rear locker and low gearing. Wait a year and you'll get a front locker too

Decent gas mileage for its size. Tows a trailer very nicely. Very noticeable and fashionable truck (lots of attention and compliments)
Cons: Limited aftermarket parts for expeditions. Those that are available are expensive. Not enough history to determine long-term reliability of the truck yet, non-alpha versions are underpowered, limited experience on service anywhere but hummer dealers in the US (bring a service manual), rear seats don't fold flat (still a huge pet peave of mine), front difs are known to explode under certain static-load conditions (ie front tires on step, then press on gas and BOOM) - can be fixed by going w/an Alpha that includes CI front dif. Not a lot of internal space. Very noticeable and fashionable truck (lots of attention and haters)
After driving mine on lots of backroads and numerous long trips (2500+ miles), I'd say it's great for local US/Canada, but I'm not so sure I can recommend it for true international expeditions. It's too new, has limited lifespan so far (for reliability), and would be a PIA to get fixed if you had major mechanical malfuction. Also, you'd be in Hummer, which means even in the middle of nowhere you'll get noticed, for good and bad
