lol, I am decent at guitar hero and I play real guitar. It's just a video game, not meant to be the real thing. Though the closest you'll get to the real thing is the drumkit(damn thing is a little flimsy though, especially the kick pedal). It's a good party game when you and your mates are drunk and is just plain old good fun.
You'll realize that it's actually pretty hard on expert difficulty even for "real" guitarists. I know I don't see many people boasting about guitar hero when they don't actually play real guitar, as far as I know I think it's alot more fun and more interesting, exposes people to decent music instead of people prancing around on a "dance pad" playing Dance Dance Revolution. Now, THAT was bullshit.