Although the shuttles are free around campus, it is a hassle to travel anywhere outside of the town. You usually need a car, cab, or an incredibly long bus ride to get where you need to go. For instance, I can get to airport in 20 minutes, but it would take me over an hour and a half (on a good day) by bus.
On the bright side, UNC has the P2P which runs every 15 minutes each evening from 8pm-3am. Weekend transportation (besides the P2P) is nearly nonexistent.