This episode is just too long.

The first 4 (5?) parts are good. But the others… Here we enter the purely science fiction episodes. The first parts, with the Doc and his companions discovering the planet, trying to escape after discovering the terrifying Daleks, are good, but let's say that it could be better.

The rest, it just seems like the producers had no ideas, the writers either, and it happened like this:

"Ok. We don't have any ideas?

- No

- Uh… What was the reason they had to go to the planet?

- The empty but not really empty liquid conductor

- Oh yeah! Ok, let's play that?

- Yeah… Come on!"

It's filler, whatever you WANT as long as it respects the principle of boring. So for the first parts I go up to 8, for the last ones it goes down to 5/10.