Hi everyone, I'm at UNC currently and have lived in both Chapel Hill and Durham. Currently, I commute from Durham (southwest, near Southpoint) to Chapel Hill and it's really not that bad, and it appears that a LOT of grad students commute from east of Chapel Hill. If you live near Southpoint, it's about 15-20 minutes to campus if you have a parking spot. If not, the park and rides are really great (~2 miles from campus). The buses run very often (every 5 minutes during rush hours) and it's free! That will add 10-15 minutes to your commute, though. Chapel Hill is a nice college town, but it's very expensive and housing can be pretty run down with pest problems. If you live in Southwest Durham, you can find very reasonably priced housing in new-ish homes. There's not really anything in Chapel Hill but the school and some restaurants. Most students come to Durham to go to the mall, Target, Wal-Mart, and do other shopping.
Durham is a lot more culturally interesting than Chapel Hill, in my opinion since it's not a college town. It has a lot of history and downtown is experiencing a sort of renaissance. There are way better restaurants than Chapel Hill and almost everything downtown is locally owned and uses uses local ingredients. There are a TON of delicious food trucks roaming around Durham, and most of them don't go to Chapel Hill because of some annoying CH ordinance. There are some unsafe areas in Durham, but they are easy to avoid. Downtown and Southwest Durham are very safe, possibly even safer than Chapel Hill.
Feel free to ask me questions! I have lived in North Durham near Duke, Southwest Durham, and on campus housing in Chapel Hill.