The only thing Rock Band Unplugged is really missing is any sort of multiplayer. Given that multiplayer is such a huge part of the console experience, its complete absence here is a bit baffling. Other than that, Rock Band Unplugged looks like Rock Band, sounds like Rock Band, and even feels a lot like Rock Band. Rather than trying to cram the full-blown console experience onto the PSP, Unplugged plays to the handheld's strengths and offers an experience that's distinctly different from the console games.
It's not quite the fantasy fulfillment experience that comes with actually drumming, strumming, and singing your way to rock stardom, and it doesn't blaze any new trails. If you're looking for a great way to take the band on the road, though, or just a way to play Rock Band that doesn't require a huge piece of plastic, look no further than Rock Band Unplugged.