Underpowered?... No!
I'll give a slightly different perspective on this one... maybe!
Now, I'm from the UK and in Europe and UK, cars with big blocks like the V8 are not that common as fuel has always been expensive - try $2 per LITER nowadays and you get the picture. Don't get me wrong the V8's have been there but only for the wealthy, as they were the only people that could afford to run them.
In the USA, you guys have had V8's for what seems like forever and as such you will compare the H3 to what you have been used to. Bear in mind that 15-20mpg in Europe/UK is still a showstopper for people looking to buy a car - if I had to go back the UK tomorrow, there is no way I could run the H3 (going to rub it in here a bit - in Bahrain, fuel is cheaper than bottled WATER - that's a fact!!)
If I compare the H3 to the Jap and European stuff, it comes out either the same or better on power for an equivalent car. I have no issues with the H3 - I love it - well, should've bought an adventure, but hey, there you go - I ran a Porsche before I bought this car, and true the H3 won't scream away from the lights, but then again, it's not supposed to is it... its an SUV, if you want power, buy a fast car, if you want something "different", capable and nice to drive, go for the H3!
If a V8 came out, I'd buy one... why? purely because I couldn't run it anywhere except here and that is the ONLY reason. For me, given the choice between going for a V8 or a 3 with Adventure package, I'd go with the Adventure package every time... If they don't do a V8, well, no biggy there... for me anyway!
The moral here is don't get bogged down on the power issue (or should I say the "no issue" as that's what it is. The H3 is a supremely capable car in every respect, it's the No.1 off road and can run with the best of them on road... GM have a new customer for life here as a result of my H3 alone!
Here's a sad fact - if BMW built the H3, the power issue would probably never be mentioned - I refer you back to my comments that you guys (luckily) have had V8's as pretty much the standard fare forever...
Look at the Land Rover Discovery, or LR3 as it's now called - you think that's any better on power than the H3?.. nope, and at how many times the price?
Buy an H3... or at the least, go rent one.. they are truly brilliant cars!!!
Cheers
JFF