Great concept, it delivers. Though even as a non-guitarist, being forced to start every song on retard mode is annoying.
There are incredibly generic stages and people. Of course the audience isn't the driving force of the game, but when you really hit a riff that has been dragging you down, and there isn't as so much as a blinking light... Well lets just say staring at the same couple club rats dancing to what looks like a hip-hop groove is a little frustrating (and really out of place).
My second major concern with the game is the music choice. Don't get me wrong, there are some real classics out there; even songs I didn't know I would like until I started getting the hang of them. Though it seems as if the devs had a bit of a hard-on for some real indy/hipster crap as well. Which wouldn't be a problem in rockband or guitar hero... you just choke it down and get through the song, never play it again... though in rocksmith you really REALLY have to know what you're doing to progress past songs (once you start getting out of the basic single-note difficulty stage).
8.5/10 because I know it'll occupy a lot of my time... And in the time already spent, I feel as if I'm actually getting real experience playing around on the guitar. Though i think my experience is slightly better than most will have, since I have "attempted" to play guitar off/on for some years. Having that very basic familiarity at least is a plus. Would have been nice if the store already had some down-loadable content... I'm going to beat the songs I like to death; meanwhile avoiding the hipster junk.