When the episode begins, the Doctor has just been shot by the Master ("Frontier in Space"). After a brief coma in which ice forms on his skin, he's okay, but in the meantime, Jo Grant has gone for help into the wilds of the jungle set with its "eye plants" and squirty plants and the inevitable giant tentacle plant. The presence of the Daleks isn't revealed until the end of the first episode. The Doctor and Jo aren't reunited until episode 4.
Trivia: There's a character called Taron--another character named after Terry's friend Tarrant? (He used the name Tarrant in both Dr. Who and Blake's 7.) Episode 3 only exists in black and white. And though the Doctor starts off the episode in dark purple velvet, between his coma and being rescued by the Thals, he changes into drak green velvet. Ever fasidious, Three!
"Planet of the Daleks" aired in 1973. The Daleks aren't the gee-whiz element in the story, the invisible Spiridons are. Yes, invisible. We can see them when they bundle into giant blue furs with magenta undertones, though, and we can see the things they carry, like bowls and weapons. The Daleks, of course, want to be invisible themselves, so they slaughtered most of the Spiridons and enslaved the rest. And it turns out they have a Dalek army in the basement, too! A Thal expedition (from the Dalek's home planet of Skaro) is also present. Luckily, the planet also has volcanoes that belch liquid ice, so those are used to deep freeze the army.
Wacky moment: the Daleks are about to blow up the Thals's spaceship, and the Doctor thinks Jo is inside, though actually she's been rescued by a Spiridon. He leaps out of the brush and yells, "No...wait! Wait...somebody's still in there." He must have been really desperate because, Daleks? Not known for their compassion. They still blow up the ship, but take the Doctor captive for interrogation, lucky him. I've never read the transcripts of the earlier Dalek eps, so it's possible this isn't as weird as I thought. Unlike the Cybermen, the Daleks didn't change as much in each appearance, because they were all written by Terry Nation (in the old series, at least).
The parts I liked most were Terry's little touches of theme; there's the bit about courage which I quoted above, a bit in which the commander of the Thal expedition angsts over how he can command without bias when his wife/lover becomes a member of the expedition, and this last bit, about war:
TARON: Doctor, we'd never have succeeded without all your help. I wish there was some way of thanking you.
DOCTOR: As a matter of fact, there is.
REBEC: Yes, Doctor?
DOCTOR: Throughout history, you Thals have always been known as one of the most peace-loving peoples in the galaxy.
TARON: I hope we always will be.
DOCTOR: Yes, that's what I mean. When you get back to Skaro, you'll all be national heroes. Everybody will want to hear about your adventures.
TARON: (Puzzled.) Of course.
DOCTOR: So be careful how you tell that story, will you? Don't glamorise it. Don't make war sound like an exciting and thrilling game.
TARON: (Smiles.) I understand.
DOCTOR: Tell them about the members of your mission that will not be returning - like Maro and Vaber and Marat. Tell them about the fear, otherwise your people might relish the idea of war. We don't want that.
REBEC: You can depend on us.
Transcript of episode.
Worth it for the serious fan of Terry Nation (that would be me) and if you want to see Jo Grant in another cute outfit.