This is a really interesting episode. You have to love the early appearance of Colonel Lethbridge-Stewart which would prove an incredible bit of continuity once he became a major part of the show's history. Troughton is a huge part of why the acting is rated so well here, and his take on the Doctor's cleverness is well done, but there's a lot of fun performances and characters throughout. I feel this story also achieves an excellent spooky atmosphere for the most part.

It can get a little boring and I definitely zoned out a couple of times though, which holds it back slightly. There's issues with the pacing, but it still is worth a watch and has great replayability in spite of its limitations.