Every single character in the game has their own theme, not a single one left out in this version of Street Fighter IV. Many incorporating different styles and instruments to try and fit with the style of character, even culture of that character. Each of these remixes are all very good, though favouring them over the original versions is up to the taste of the user of course. Overall all of them are solid and great to listen to during the fights in the game. The character themes are more enjoyable to listen to then the normal background music that plays during the stages, but they themselves aren't bad, just completely overshadowed by the character themes.
Opening Theme of Street Fighter IV
Ryu's remixed theme
Seth's (Final Boss) theme