Currently in the middle of this one in my full watch and it’s one of my favorites so far. I think in part that’s because every episode has its own contained story, which helps it to avoid dragging like 6-parters tend to do.
I must say, The Keys of Marinus isn’t your average serial, it definitely gave me the vibes of a miniseries like Flux or Trial of a Time Lord while watching it.
It’s good but not perfect. The unusual fetch quest narrative makes it stand out a bit. There’s some of Terry Nation’s lazy writing present. But there are many great parts, such as Part 2 and the trial towards the end. Vasor is one of the earliest creepy characters on the show; just look at how he harasses poor Barbara.
The Voord were created in hopes of them becoming the next Daleks, but we’ve never seen them on the show since. I find them a bit silly, but I guess they could work if redesigned somewhat.
I remember enjoying this and I think that the quest narrative helps keep things interesting. The Voord definitely need a TV reappearance. Especially if RTD can do something interesting with and not just include them to have a returning monster.