Yeah, I have no idea. I'm just glad it finally came through! My wife was out all last week, so I could probably have played untold hours then (which is another reason I was chomping at the bit), this week I'm crunching on work, and have so much less time, so I'll only get to play in small spurts.
Overall I'm pretty pumped about this game, it is so nice to be able to play with my own guitar even if I find the interface confusing.
I do notice lag though, I'm trying a few different set-ups... One is HDMI to TV, and Optical directly from the Xbox Slim to my receiver, the other is HDMI to the TV and headphones for audio (headphone jack coming from the TV out). Both of those make me feel as though I have a delay pedal on the stack, so I might try component cables to the audio to see if that helps at all. I have the "Game" mode on my 46" 1080p LCD on. Normally I just do HDMI for video and audio, but that's the explicit no-no on their charts, so I haven't even bothered to try that out.
My understanding from reading a few posts was that optical directly from the Xbox Slim (which has a direct optical out without any adapter) to the receiver should actually not pose too much lag (it was more the optical from the older xbox via the adapter that was the problem), but I've heard a few conflicting reports so am not really sure on it...