An awesome multi-platform game that has become a pop-culture phenomenon due to it's ability to make the player feel like they are a talented guitarist without having to waste any time actually leaning how to play a guitar.
Like all things that experience fast widespread success, and cause hot topics of conversation, it has it's detractors. Mainly guitar-players who are angry at the game's ability to make them look bad, and because they didn't know about it first. Like all critics of this type, they take an elitst stance and usually combat any conversation regarding the game with statements like 'Why don't you just play a real guitar'. Or 'It's just a poor man's version of a real guitar', ignorant to the well-noted fact that no girl has been impressed by a guy who can play the guitar skillfully since 1995.
It is this shift in the female gender's attraction from the traditional guitarists to non-instrumental vocalists that has garnered much resentment from the guitarist community. In addition to the fact that being a member of a small band is now less attractive than being a Level 639 at Warcraft.
It is also worth noting that while there are other games that simulate the experience of a sport or activity, such as the Tony Hawk's Pro Skater franchise, Dance Dance Revolution, 'music-making' games, and Sim-whatever; which do not recieve the same hostility from their peer groups. "Why don't you just go and skate/dance/compose/build your OWN theme-park. This is understood to be because of the "Guitars-are-lame paradox", where being skilled at a video game replicating classic guitar songs looks more fun than actually playing them would be.
Subject A: "Hey I've just bought Guitar Hero!"
Subject B: "Ughh, philistine. How moronic. Why don't you just be a REAL man and learn how to play guitar for REAL. Heh"
Subject A: "Errrm, are you aware that you're not in 1995 or a movie?"
Test subject (female): Will you (subject A) come over to my house to show me how to play Guitar Hero?"
Subject A: "Yes."