I am really hoping they release a RB4 for Wii U and allow all DLC to transfer and have all current instruments compatible with the new game!

In party play, this tends to be really hard to use; people don't really want to take the time to log in and out, and due to the limitations of the game's controller scheme (see my edits to the review on the Rock Band 3 Wireless Pro-Drum and Pro-Cymbals Kit for Wii) there can be issues with getting the right instruments into the game at the right time without

The musical instruments to be used with this product are not easy to find at this point.

That is, if you want to be playing a bunch of fake instruments, singing off key, and have other people in the house give you strange looks.

I hope more future development is put into a better multiplayer experience with all instruments and vocals fully available

It adds a new level of difficulty, but I wouldn't recommend putting down that kind of cash unless you're actually interested in learning the instrument or skilled enough to play at that level