With two mics right out of the box, SingStar Rocks is an instant party. Even still, it only costs as much as the average new game. This is made for multiplayer; single-player is devoid of a meaty mode of its own. Medleys, battles and duets await to amuse groups (hopefully intoxicated ones, to boot). Sadly, "Love Shack" is the only true duet.
Bonuses and extra songs are absent, but SingStar does allow for a playback of your performance - with tunable microphone volumes. Save them to your memory card for later blackmail use. The rankings and scoreboards will keep you coming back for more, too. SingStar Rocks also supports the EyeToy, but it's bad enough to have to hear your friends murder hit songs; you don't want to see them doing the white-guy cabbage-patch to DJ Jazzy Jeff and the Fresh Prince on top of it.