We went on a 9pm ghost tour offered by this group. The tour leader had good stories with average delivery, and by the end I was a little spooked. (No ghost sightings, though. Go figure.)
The best part of the tour is that you get to see Plymouth. These are places dense with history, and there are some really neat stories. (There was also a bunch of unsubstantiated gibberish about poltergeists. After watching Twin Peaks, I've had a hard time being scared by many ghost stories.) There are alleys and haunted houses and graveyards and such.
You get to carry these cute little lanterns that identify you as part of the tour group. (Occasionally you get to hear the tour guide interrogate people who don't seem to be holding lanterns - "are you with my group? did you buy your tickets yet?".) At the end of the tour, after spending about an hour and a half traipsing around historic Plymouth, you get to give it back.
The Lantern Tour we went on wasn't life-changing. But it was informative and interesting in the best way, and I'd certainly go on one of their other tours again.