It's amazing that South Carolina can have one of my all time favorite cities (Charleston) and one of my not so favorite (Columbia) within 2 hours of each other. Totally different worlds too. Columbia has like one really nice area and then lots of armpit, as TigerTown said. I did, however, find some great places to eat there, and even had cheese grits for the first time. But overall, just drive through it on your way down to Charleston. I love Charleston.
The people I met in Columbia were very nice, though, so I want to make it clear I'm not hammering on them. What I find hilarious is the internal state feud between Clemson and Gamecock fans. Gamecock fans go out of their way to marginalize Clemson fans, even saying that Clemson is technically not part of the state. One of the guys I met on business worked in a facility loaded with Gamecock fans. His office was decorated with all kinds of pro-Clemson items and all kinds of anti-Spurrier crap he'd pull off the Internet. He'd hang that Spurrier stuff on his door to get a rise out of everyone. I'm not an SC fan, so I always sided with the Clemson guy. He was outnumbered.
On the other side of the state, Greenville is a great little town too. Great places to eat downtown.