There are certainly some gems to be found in the inconsistent Pertwee seasons which followed the phenomenal season 7, and "The Curse of Peladon" is among them. This is a wonderful, thrilling story with a superb cast of characters, a great location in the medieval planet of Peladon where the progressive vs. conservative debate is raging, and just some wonderful writing and one excellent fight scene towards the end of episode three.
"The Curse of Peladon" is one of the better politically-conscious Pertwee stories. The politics don't get in the way of the storytelling, which is certainly very politically-oriented in itself, I suppose, but there's little heavy-handed moralizing here, it's all presented rather fairly and simply. What's wonderful about Brian Hayles' script here is how excellent all the supporting characters here are. Not only do we get a return of the Ice Warriors, one of the all-time greatest Doctor Who monsters (who don't play a particularly villainous role here, but are still very entertaining), but also a couple of other amusing aliens (Alpha Centauri's unfortunately phallic appearance makes it hard to take the story too seriously, though). The really superb guest characters here are King Peladon (played superbly by David Troughton, son of Patrick) and Geoffrey Toone as Hepesh, who is doing all he can to fight off Peladon's joining of the Federation, which he perceives as something that would threaten Peladon's traditions and would essentially end with them becoming slaves.
Both Troughton and Toone are excellent here, and it helps that Katy Manning and Jon Pertwee are both on top form as well. Jo's given a fair amount to do here, and I think it's one of the best stories overall for her character (not that I buy into the whole 'Jo was useless' thing, I found her to be quite a good character and her relationship with the Doctor to be very interesting), even if what she's involved in is unlikely to please the ultra-feminist portion of the audience.
The episodes are directed very well, the scripts are very good, and while the story may not ever reach true greatness, it's both a fun romp and an interesting political/social allegory which is still surprisingly relevant today.
Episode 1: 8/10, Episode 2: 8/10, Episode 3: 8/10, Episode 4: 8/10
Average: 8/10