I play the drums but haven't played Rockband so I can't comment on that ...
My brother is a guitar teacher and his claim is that he has never had as many really good guitar students as he has since guitar hero was released. Part of this is the increased dexterity in your fingers that guitar hero provides, and the (very) basic understanding of notes and frets that guitar hero teaches ... Truth be told, the main reason is probably that the motivated guitar hero players who complete the game on uber-hard with 5 stars (including all the bonus tracks) are already far more motivated than the typical kid who saw a band at a concert and decided to learn the guitar.







