I've been here for about a year, and I get by just fine without a car, in fact, only two people in my cohort have cars, and I know a ton of other grad students without cars, it's very doable, especially if you live in West University, Pie Allen, Downtown, or Sam Hughes, etc (really any of the neighborhoods near campus). I live near downtown and campus is a very easy bike ride away, and I don't really find myself needing to leave the downtown/campus area very often.
The buses are not great. Crowded and they stop running very early. It makes going to see a later showing of a movie or anything like that, kind of a hassle. The biggest problem for me has been getting groceries, but I recently discovered that safeway (a bigger grocery store chain in the area, think Kroger, Fry's, Food Lion, etc) deliver's for a very reasonable fee, and if you are patient you can very easily get coupons for free delivery. I think the standard rate is like $13, but it's very easy to get that reduced to around $6-7 even without coupons. And speaking from experience, it's totally worth it just to avoid the hassle of dealing with getting grocieries on the bus. I really wish someone had told me about it my first semester here.
Also, Sociolite, feel free to pm me, I'm in the Soc department so if you have any questions let me know.