t appears that Rock Band 2 for the Wii might actually not be quite as half-assed as its predecessor.
The following things can be gleaned from an IGN article on the subject.
The good news: Most importantly, the Wii version will have all the DLC made available for the 360 and PS3 over the last year. That’s a lot of songs. The full band creation/world tour functionality will be included this time, as well as the new battle of the bands mode, which updates dynamically with new challenges. You will also be able to use your Guitar Hero III guitars.
Now the bad stuff: DLC will be downloadable to SD cards, but must be copied to the Wii’s internal memory to actually be used. Exactly how inconvenient this is remains to be seen. Rock Band songs on the HD consoles are between 20 and 40 MB, but they might have invented some compression for the Wii due to its disabilities, and the songs might be smaller because the Wii’s audio hardware isn’t as advanced. (Note: the last sentence is total speculation.)
Additionally, the art studio used to create band logos, tattoos, and custom clothing and instrument art has been removed, and there will be no way for Wii owners to export their Rock Band 1 songs into Rock Band 2, or access them in any way other than playing the old version of the game. It’s also not coming out until December.
It’s clear Harmonix and EA have really tried with Rock Band 2 on the Wii, and it will be a competent product this time around, but if you want the best possible experience, you’ll still have to look to the Xbox 360 or the PS3.