I finally got around to dropping the money on a cartridge of this and I spent hours playing through it last night and getting all the endings and trying all the characters. It has to be the best traditional beat-em up I've played, way better than SoR2! All I ever heard was how this game was a disappointment because it was "butchered" in its translation to the US/EU, but really, the game we got is still great. I enjoy the plot, I like the new character colors, and I watched videos on youtube and really, I'm more than fine without Ash being in the game.
Great music, gameplay, varying levels and endings, unlockable characters... what a great game! If you haven't played it, get on it! Everything hails SoR2 as the best beat-em up, but I think this easily outdoes it.
If you enjoyed SOR3, you really ought to search the web for SORR. (SOR Remake by Bombergames) You're not gonna find the project on the creator's website since Sega ordered it to shut down, but it should be fairly easy to find by googling it. It's essentially the entire series (and then some) combined into one game. It has four sets of levels (1 level set for each game and several unique ones) , all characters and enemies from all three games and tons of unlockables and extras. It also has quite good AI which is both a bad thing (the enemies WILL kick your ass the first few times) and a good thing. (you can play cooperative with a very reliable CPU partner)