yes, it is thinner if i can believe the specs online for the HD. the shear comes in under 10mm (9.7mm based on my engineering scale and converting units).
it's not as thin as the phone itself or a bumper i saw the best buy guy had on his, but it's very thin overall and a major selling point to me.
(i have already returned and traded in two other cases including the Speck Candy Shell which was about 11mm thick -- i liked this case and its fabulous buttons, but after a few days, it looked horrible with all of the scratches)
i agree, one downside of the sheer grip is the slight showing of the slate aluminum.
not the perfect case by any means, but the best i could do locally and i feel i can now sit tight for a few months to see what else turns up. but overall, i'm happy with it.