This is, all in all, a fun episode that I would gladly watch again and enjoy. It's paced better than many episodes in this era, has interesting side characters and quite a bit of heart, as well as fantastic atmosphere.

I think my main complaint would be the villain. Mr. Ring-a-Ding just wasn't very good. Some of his scenes felt powerful, but for the most part he was a little annoying. The "don't make me laugh" thing was an obvious set-up and felt very strange and kind of stupid in the introductory song. I didn't feel the flashbacks were necessary, especially after the even shorter-term flashbacks in the very previous episodes, and the harbinger reveal was groan-worthy.

On top of that, the animation was clearly done by computer rather than using cell animation, leaving it in a sort of uncanny valley that made it hard for me to focus on the actual story. When the Doctor and Belinda got animated it looked really stiff, and made the already forced-feeling moment of honesty between them feel even more wooden and out of place, which led to me being completely unable to believe that Belinda learned to trust him more during this episode. I do like how the "real" body Lux was building was clearly referencing those youtube videos where a sculpter makes "X but realistic".

The thing is, there's a difference Whoniverse story with a near-identical premise: Torchwood's From Out of the Rain. I can easily compare Lux to the Ghostmaker and say that I by far prefer the latter.

Let's move on to happier things. I really liked the scene with the fans; while I was hoping for a deep cut with the favourite episode, I must admit them all being so adamant about Blink was quite funny. It was an exciting moment, and I enjoyed it. It was nice to have a bit of downtime before the third act with a bit of meta humour.

I think the episode handled segregation very well for the runtime available and considering the episode wasn't about that (much better than Dot and Bubble handled racism, in my personal opinion), but I'm a bit miffed with how surprised Belinda was to learn about it.

The set design and costuming were great, though I'm again left begging for them to show us the wardrobe room.

This review might be leaning a little negative, but I really did have a good time.