We had one open about 4-5 months ago by us, and I thought it was fine then but the burger wasn't quite as flavorful as I would've liked. Since then, the burgers have been great and the hot dogs are excellent as well. Love the toasted buns they use.
Vienna is a quality hot dog, and while Freddy's doesn't do its dogs in the Chicago style (which I think is overrated anyway) I give it a B+. The bun is seriously one of the best I've ever had for a hot dog, though. It gets an A+.