Well, it depends where you want to go. If you want to get downtown, the light rail stops right outside of campus and takes you directly there. If you want to go to the museums, you can walk or do it by light rail. If you want to get to shops and restaurants at Rice Village
Rice Village you can walk or take the shuttle bus. (Note that this is a 19-block shopping area that's located 2 blocks from the Rice campus with tons of great restaurants and shops.) If you want to go other places in Houston, you would need a car -- but tons of students have cars so that's not much of an impediment.