I was just thinking this the other day. I played a little USM and SM3 and was reminded of how terrible the music is. In USM, it sounds like generic Super Nintendo era music. SM3's music while free-roaming as black-suit Spider-Man is just terrible, eery sounds that can't really even be called music. Even SM2's music was just constant drum loop generic music. I never liked Web of Shadows' music much, but I now might think it's the best of the 4 free-roam games.
I wish they would follow the Assassin's Creed way of playing music in the game. In those games, there's a theme for each city you visit that plays on a loop. If you get into a fight, a new theme will fade in and play for combat music. If you're running from guards to try to escape, another theme will sometimes play. For Spidey, I'd like to see one or two theme songs that play when you're just hanging out in Manhattan. Maybe a different track for night and day, whatever. But it would be nice if a new theme would start playing when you reached a certain speed of locomotion and started swinging, falling and Web-Rushing around. It's so weird just hanging out on a rooftop admiring the view in SM2 and hearing the fast-paced, generic drumbeat track playing. I want to hear music that's more relaxing when there's no action going on. Otherwise, it just feels out of place. And of course, a separate combat music track would be nice as well. This is all just a suggestion for free-roam gameplay, and doesn't include all the different tracks that could play during important story moments and indoor levels.