In case you tire of always playing lead guitar, the new co-op mode offers the chance to play rhythm guitar or bass. It's a nice bit of variety and actually feels like you're working together rather than simply playing side by side. Needless to say, this one's going to be a big hit at parties - especially after a few drinks have been passed around.
Not too much has changed visually, though there have been some minor upgrades. The on-screen fret bar now shakes when you biff a chord, new characters have been added and the performance spots feature more background detail. If you have a fancy HDTV, Guitar Hero II sports native support for both widescreen and progressive scan. There's even a calibration option in case your LCD or plasma suffers from display lag.
An evolutionary step forward, Guitar Hero II improves on its predecessor in nearly every way. If music games are your thing, this one should be on your watch list.