I've never owned or heard a pair, but from what little info I have found, it would seem that they would be great for rock and electronica, but fans of the more mellow genres may find them a bit grating.
They have a good bass response, but are a bit forward in their balance, so if your kit is bright then I'd guess they may not be the best idea... That said, the '81s do look good and I was nearly tempted myself.
I used to have a Reference series 5.1 setup when I lived state-side and it was really good. They are very exciting forward sounding speakers that give you a great sense of dynamic range and detail, but, as someone else mentioned, these qualities mean that they can tire your ears after extended listening sessions. While they were enjoyable for music, they really shone when watching films. Nothing like the pure impact of horn-loaded compression drivers for cinema (all cinemas tend to have them behind their screens). I used to demo the attempted landing scene from Air Force One for friends and the dynamics of the speakers really gave you the impression that the 747 was flying left to right across the middle of the room every time it passed the camera.