While the PC version of Street Fighter IV is lagging months behind its console brethren, the core codebase for the computer version is actually much, much older. The arcade game from which the PS3 and Xbox 360 games are derived is based on PC architecture, so in essence this home game is an enhanced rendition of the "real thing". That being the case, it's equally as brilliant as the console games in terms of the raw gameplay, but the graphical assets can be scaled up to whatever your system can handle.
For the Street Fighter IV purist (and we know how many of those there are), the difference could be remarkable - I mean, kit yourself out with the right equipment and you can play SFIV at 120FPS if you want. However, for the rest of us, the improvement will be marginal at best.