Graphics/tech issues aside, I thought it was great until the last half hour-ish. That was a whole lot of tension and build-up to nothin'... I wanted something big and scary to shoot my BFG rounds at! Also really could have used a post-story free roam mode.
Once again, though, you gotta give Carmack credit for talking frankly to everybody like that. He really is one of the last of a dying breed of genuine game developers. I bet Tim Willits/Pete Hines cringe a thousand times during one of these long-ass keynotes.