We've visited the race of the Ood before, where they were a collective race of servants that shared a hive mind. Now the Doctor and Donna visit their home planet, and discover they are being enslaved by humans. To the rescue!
It was a heavyhanded moral point being made this time - slavery is bad! Servants should have freedom! But it was handled in the usual SF superficial way, though not badly. It is meant to seed a thought into young minds, like most childrens' TV and literature, I suppose.
Last week's episode the traditional story arc we all know is coming was touched upon when the Pompeii soothsayers predicted "She is returning" which we all know was a reference to Rose. They also said to Donna "There is something on your back." That's a good mysterious omen to conjure with.
Well, this week the Ood said something similarly prophetic: Click for spoilers
A good episode for character development, though. It cemented my thoughts on what Donna's role is - to keep the Doctor grounded. She's more confrontational, but clumsily human, which serves to be a closer representation of how humans would really handle the wonders the Doctor shows us. Blundering in and saying the wrong thing, but meant in a caring and empathetic way.
I like this season so far. No duds yet.