When it comes to 2D, the Saturn gets the last laugh. As the fourth Capcom game to support the 4MB RAM cartridge, Marvel Super Heroes vs. Street Fighter joins a collection of arcade-perfect conversions of fighting games.
The concept behind MSHvSF is simple: They took X-Men vs. Street Fighter, replaced a few of the characters, and shipped it. The backgrounds were updated a little bit, some of the music was altered... it's basically the same game all over again. Even the boss from XMvSF is identical, though a robotic version of Gouki has been added as the game's final boss.
Graphically, the game is very, very good. The sprites are extremely well animated, and the backgrounds are all packed with movement, giving the game a nice, busy look. The additional RAM ensures that every frame from the arcade version is displayed on the Saturn. The game also has a lot of speech, even more than XMvSF.
So, it's a perfect conversion of the arcade game. That much we know. But that doesn't really stop it from being a near-carbon copy of XMvSF. That also doesn't stop it from having the same button-masher-friendly gameplay as its predecessors. It still manages to be reasonably fun, and it does have Norimaro, the Japan-only character (which, incidentally, is causing Capcom to chase down people that are importing this game, as there are licensing issues involving the Norimaro character).
It's pretty much a given that this version is going to easily smoke the PlayStation version, which, while it will be coming out in the US, will be just as limited as the PS version of XMvSF was. If you're still interested in the Saturn, then this game is definitely one to import.