I am totally biased, as someone who spent years and lots of money on equipment, but I hate that game. Never played it, but I hate it. Again, I am biased. Read above, I spent money and time actually learning some of those songs... But I tell ya, it is FAR more rewarding to learn to play.
Its HILARIOUS really when you think about it; when guitars first started getting popular (100s of years ago) they were lambasted as being too easy to learn. Professional muscians made fun of guitars because they said anyone can sound good on them with a little practice. Indeed, the whole layout of a guitar is designed for that, it is one of the easiest instruments to learn while at the same time being impossible to master. I am paraphrasing Eric Clapton on that one.
So now what do we do? Make the easiest instrument even easier. Sure, I guess guitar hero couldn't be counted on as an instrument... but still.
But yeah, I am biased...