It's not as awesome as good 'ol Pokemon Stadium, but it's still pretty decent!
If you have Diamond or Pearl (I think it connects with Platinum too), you can use the pokemon from those games...and you use the DS as your controller to select moves! I have no idea if the online battling scene is still big, but that can be pretty fun too!
Obviously you've already bought it, but I recommend getting Pokemon Colosseum/Pokemon XD instead. (I think XD is the sequel to Colosseum). Both are for Gamecube, and they have legitimate storylines and are actually really fun to play. Battle Revolution is more like... random battle but with Wii graphics? I don't know, let us know what you think!