It really is so hard to be unbiased about this, I've seen it so many times it's near impossible to watch it "new". Whether I know every line because of repeated viewings or because they're just so damn perfect - as written and performed - that they stick in the memory, I can't be sure, but any show would be lucky to have as good as start as Doctor Who did.
It's interesting to watch the first episode after the pilot, as I now appreciate it even more, if possible. As it starts, we are presented with the same mystery as before, but the simplistic direction communicates better how ordinary Ian and Barbara and their lives are, thus drawing me more into their plight. The time between the pilot and this seems to be for the better as the technical problems don't happen again. It's altogether more polished than the pilot and the actors seem to have found the characters. As Ian and Barbara discuss the enigma of Susan, at this point I'd happily watch a series with just them! William Russell and Jacqueline Hill are terrific, given the time to pore over every line and deliver it just perfectly.
As the action shifts to the junkyard, William Hartnell finally makes his entrance as the Doctor - the First Doctor is my favourite (at the moment), but although intriguing and certainly likeable in this story, he doesn't become a sympathetic character until later. Hartnell plays the Doctor with an air of cheeky superiority in his opening scene - something I'd usually associate with David Tennant's Doctor - and comes off differently than in the pilot despite delivering the same lines. Admittedly, his actions in the scene in the TARDIS - kidnapping the schoolteachers so that they don't tell people about him - tally more with his pilot episode persona, but here they still work because the performances and the dialogue are so great. The Doctor is rather inconsistent in how he treats the "savage" humans - we never think he means them harm, but what would he have done if the TARDIS dematerialisation controls hadn't been accidentally activated? We can only wonder, especially considering as soon as they run into trouble in the second episode he can't apologise enough for what he's done. Of the four regulars in the TARDIS scene, Carole Ann Ford is the weakest performer, as before, but she improves on her previous performance and is quite likeable in a safe environment, although her characterisation, like the Doctor's, has changed drastically since the pilot, with less otherworldliness this time around.
The scene of the Doctor explaining what the TARDIS is to the disbelieving teachers is pure magic. There's something about this episode that makes every single line seem like perfection - certainly everything flows well without anything sticking out like the 49th century line in the pilot. As the credits roll, the TARDIS takes its antagonistic crew to a prehistoric landscape, but at this point I'm more interested in how the sceptical Ian and Barbara are going to react to seeing the truth of the time machine for themselves than what that shadow is.
We're in 100,000bc for the rest of the story, as the TARDIS crew are kidnapped by a tribe that has forgotten how to make fire. There is something about the content of these episodes that makes them the wrong choice of story to follow the first episode, however in this case the quality of the first episode makes the difference in quality seem greater; I'd say they have only three key failings - they're not a natural continuation of the story started in the first episode, so after a bucketload of character development from the regulars, with nothing but the four of them interacting for 25 minutes, the story is hijacked by some cavemen, and the character moments are reduced to exploring how they cope with desperate circumstances, when survival is their only ambition. That's interesting too, but quite a u-turn after the first episode and not at all what we were expecting.
The second failings is that they focus too much on other characters, with scene after scene of cavemen politics when we want to see more of the Doctor and the others. The third is that they're simply not as interesting as the first episode, but that isn't a huge criticism, as the first episode is perhaps the best single episode the show ever turned out.
The 100,000bc episodes are not entirely disappointing. In fact, they're perfectly good, but they're just neither wanted nor needed at this point. After the TARDIS lands, we get an extended scene introducing the tribe, showing us Za and his dilemma, unable to make fire. All through this scene, I was thinking "meanwhile.....?" expecting (and hoping for) a shift back to the TARDIS at any moment. Unfortunately, this persists all through the rest of the story, even when the regulars get captured, I just want them to get back to the TARDIS and let the real story continue.
When you think about it, the cavemen story ties quite nicely with "An Unearthly Child" - the Doctor even calls Ian and Barbara "savages" at one point early on. Suddenly they're taken out of their comfort zone and the schoolteachers are confronted with people they would consider savages and try to reason with them (well, just Za) like how the Doctor tried to explain things that were beyond their understanding earlier on. Tribal politics aren't very interesting, but the dialogue is engaging and the writer successfully builds anticipation of the discovery of fire.
The TARDISeers are let go by the Old Mother, who doesn't want them to show Za how to mak fire. I liked the Old Mother character, a person so set in their ways that they will defend their way of life even when it is about as miserable a way of life as you can get. As for the other cave people, Kal is a forgettable grunt and Za was interesting because even when the strangers save his life and show him fire, he still won't let them go. All of this I found completely believable - in fact, if they have behaved otherwise it would have stretched credibility.
The group escapes through the forest, but Ian and Barbara insist on stopping to help the wounded Za. The Doctor tries to bludgeon Za so that he won't slow them down, but Ian stops him. In any other context, I would find the Doctor deciding to kill someone in such a graphic manner shocking, but at this point things are desperate, the Doctor and his comrades are dirty and bloodied and exhausted - in fact it's Ian and Barbara's decision to slow down and help Za that had me rolling my eyes. The goal is to establish the humanity of Ian and Barbara, but given their backgrounds I would have been expecting them to be even more determined to get back to the TARDIS than the Doctor and Susan, who I expect have been in life-threatening situations before.
The end of episode 3 - an ambush and re-capturing outside the TARDIS - is a disappointment, because it means a whole more episode of cavemen! Well, there is still that fire dilemma to resolve, and Kal, the clear "villain", is still around. Notice that as soon as Kal is killed in episode 4, Za is free to turn villain on the regulars. Before that, he has to show some redeeming features so viewers will root for him in the struggle in the cave.
The Doctor gets his first proper heroic moment early in the fourth episode as he goes all CSI on Kal. I just loved this scene, and it shows that the Doctor hasn't just been thinking about himself and how exhausted he is. At this point, Ian recognises him as the leader of the group - before that they had been subtly fighting for superiority.
The fight between Za and Kal is surprisingly brutal - clearly Doctor Who had been violent from the start, even though the Doctor is not directly involved. The TARDISeers escape by burning skulls, to pretend that they have killed themselves - the effect is rubbish but it would probably convince the dumb cavemen. It's a huge relief when they're back in the TARDIS, because the character development can now resume. In retrospect, the cavemen episodes were watchable enough, but they were still only a diversion from the real story.
I think the strengths of the cavemen episodes are often ignored. They are really good, they just came along at the wrong time, and for that reason that disappointing feeling is amplified. The regulars get about as dirty as they're ever going to get, and for one of the few times in the series, despite the relatively low stakes and simple villains, they could actually kill our heroes quite easily. We believe in the danger. Despite the budget, the episodes look magnificent. The problems that would beset the series in its later years are nowhere in evidence. It's a slick, polished production that is a worthy, if misjudged, way to launch the series.
Horror quotient - The cave of skulls is quite hokey and the forest is creepy, but there's little genuine horror in evidence.
Comedy quotient - It's quite remarkable how serious the show is at this point. You'd never think the series would soon get much more lighthearted.
Drama quotient - This story has drama in spades. Tension between the regulars, between the cavemen, between the regulars and the cavemen. Believeable peril and you really feel like you're there with them. I was feeling every emotion the characters were through their various tribulations.
Full marks for the first episode, but the rest drags it down slightly.