Guitar Hero was a great game before Neversoft took over the development. As soon as Harmonix stopped working on it, the quality significantly drop. That's a fact that I found out pretty quickly as soon as I tried Rock Band for the first time.

On top of that, Activision went out of their way to to oversaturate the market. Ever since '07(?), they've been releasing two or three rhythm games per year. They released probably a decade's worth of rhythm games since GH 2. It's ridiculous.