It's right around 150 miles and will usually take me about 3 hours. 331 varies from 4 lane divided at 65 mph to 1 lane each direction going through a couple of small towns. Luverne and Florala are the 2 towns where you have to make turns, but they are nice older towns and I enjoy seeing that part of America avery now and then.
There is some construction south of Defuniak Springs as they are making it into a 4 lane divided, but having traveled that recently it only effects a short section at a time. I would avoid Saturdays on 331 south as it seems the whole world is going to the beach that day. The bridge over the bay there is a non toll bridge unlike the one from Niceville to Destin.