I first saw it when the BBC did that series of repeats of a story from each Doctor, and obviously a lot of Troughton is either too long or too lost, but it just didn't quite feel right in such iconic company as The Daemons. I think it might be another of the stories which, cut to modern 45-minute length, could be excellent, but as is it drags too much and too often.
But hey, if you really like it, try Steve Lyons' first two books...