Went to Sidmouth a few years back, wouldn't go again. Not enough folk song, too much diddley-diddley, dancing, and "world music". One pub seemed to have the same tune being played all day every day all the time I was there. Which wouldn't have mattered but I had to walk past it when going from my hotel to the main arena. What singing sessions did exist were very in-groupish. "Now my old mate from Exeter would like to sing the same song he sings every year...."
There were some great concerts, and most people seemed to be enjoying themselves no end, my daughter loved it and went again the following year. So I guess it's mainly me being a non-singer non-musician non-dancer. However, my wife took part in the Sidmouth choir, and really enjoyed that, but she wouldn't go back to the festival either. We just love folk songs, and Sidmouth is not the place for that particular niche.