If you're interested in Rev 2 (yes, Rev 2, not Revelator 2), it would probably be better to go ahead and buy this at $20. Word on the street is that the DLC upgrade to Rev 2 will cost $20, so you can get this version and play it for now and decide if you want to spend the extra $20 to upgrade later. The consensus seems to be that the retail version of Rev 2 will cost $40, so the only foreseeable reason to wait would be to save hard drive space, but even then there's no telling how much of the update will be on disk and how much will be DLC.
By the way, this is an excellent fighting game and you should consider it if you have any interest in fighting games. Very fast-paced and deep. Every character plays very differently, and player interaction is emphasized greatly. It also has the best tutorial/challenge mode in any fighting game ever, period. The tutorial gives you an obstacle course type layout that helps you get comfortable with movements and the basics, and the challenge mode goes over advanced techniques (including some option selects), how to play the different characters, and how to combat the strengths of other characters.
Just don't expect to mash buttons and take games online. If it's any indication that it's a game worth learning, it's the online competition.
