Guitar for Grownups is a group class-based program. The instructors are knowledgeable and patient and are full of great tips and ideas. They are careful to try to make sure the class "gets it" before moving on to the next song or concept. Best of all, the music used in the class is stuff you'd be proud to play for your friends, not just some canned music book songs.
I would recommend this class for anyone who doesn't want to pay a lot of money for private lessons but wants to make some good progress with their guitar skills.