I agree the luggage space is limited, but for a Vette owner, it is great and comparing to my Jeep that I take to Utah every year, the Hummer is fantastic. But it is just me and sometimes a friend or my kid. Next week, after I pack in two large camera bags, two duffles, misc. gear, and then my kids two camera bags and duffle bag, I might have a different opinion.
I found the cruising to be ok in all of TN and parts of NC; granted the grades aren't as steep, and it did some downshifting to 3rd a few times, but it is what I expected for an auto/220 hp engine moving 4800 lbs. Guess in two weeks I'll find out how it acts in I-70 through CO, but last year in my Jeep, fully loaded, in third gear (manual trans), I could only obtain 65 mph up a few of those long passes.
Seats to me are very confortable, but I do have the leather, and have only driven a cloth seated vehicle around town; not on long trips.
However, a vehicle with this HP to weight ratio is not for everyone, and not sure if it would be the vehicle for me if I still had three young boys and went on extended trips with them.