I was going to write a longer review, but ThetaSigmaEarChef's already captures exactly what I think! Very good story, I had fun the whole time.

Some more specific things I liked:

• Jo on her first trip!
• The Doctor giving her a lil forehead kiss when he goes to save her from the Primitive City (great name for a city)
• The Doctor's magic show for the Primitive guard
• All of the side characters were great, I loved them. Gasped and covered my mouth when the ship exploded! I really thought they had all died, like a fool ahahah
• Captain Dent looked like Judge Frollo, which made him extra evil.
• The Master trying to kill the Doctor+Jo on one second, offering him half the universe the next. Make up your mind, dude.

And this exchange made me laugh out loud:

MASTER: My credentials are immaculate.
DOCTOR: Forged, of course.
MASTER: Of course, but immaculate.