GameSpot got its hands on the PlayStation 2 version of Harmonix's Rock Band, due to ship next week, and found that it's a very scaled back affair compared to the already released version. While it's no surprise that online play is nowhere to be found on the PS2 port, as is the potential for downloadable content, it seems that a handful of other aspects have been left on the cutting room floor. According to the preview, the last gen version of Rock Band features a much simpler, more linear World Tour mode. Character customisation is gone, as is the dynamic of accruing cash and amassing a fan base.
Outside of online play, these aren't the kind of core elements that will keep most players coming back to Rock Band, so I doubt these downgrades will sow much consumer rage. The lack of downloadable content may, but I wouldn't be surprised to see MTV Games and Harmonix issue expansion packs of songs that aren't included in the original.
Rock Band Hands-On—The PS2 Edition [GameSpot]