The Daleks is a very important story in the history of the programme. Not only does it introduce the Daleks it saves the series as well. The boost the Daleks gave to the ratings ensured Doctor Who would last longer than thirteen episodes, giving Verity Lambert and David Whitaker further opportunities to show their bosses and the audience what they could do with the programme.
It is a good introductory story for the Daleks. They are on their own planet (something that will not occur again until The Evil of the Daleks) and the story reveals some of their history, particularly their relationship with the Thals. Their aggressive philosophy is revealed in many different ways, e.g. when they announce they will change the environment rather than themselves in order to survive, and the line Every problem has a solution has a narrow minded determination about it that even upsets the Doctor. Their callousness and cunning are also very clearly shown, e.g. initially planning to withhold the drugs from the crew and then changing their minds for their own ends, failing to be fooled by the crew breaking the camera and adapting their murderous strategy (from dropping a neutron bomb to releasing radiation from their nuclear reactor) when they realise Daleks need radiation to survive.
They also have a couple of attributes never seen in the series again. The way they speak is not so loud or monotone as they will later become. Their rather fast flat way of speaking is chilling for they are dismissing the Thals and the crews lives so casually, e.g. the line Then they must die is more disturbing than if it was uttered in a loud fanatical way. Their contracting lenses are also very effective the sense of a living being inside is clearly felt, especially when one Dalek starts to die when the Thals drugs are administered. This is also a unique story for it is the very first time the Doctor encounters them there is a classic moment when the Doctor is first interrogated by them in their control room on his knees. Hartnell conveys puzzlement, fear, anger and panic in this scene very good acting, the danger increased by the Doctors failing health due to radiation sickness and the fact that he really doesnt know what hes dealing with yet (and he believes the Daleks when they tell him the Thals are mutations).
There are some other classic moments in this story as well. The Daleks ambush is a clear sign of racism in action and is more dramatic because it occurs after Temmosus humane and hopeful speech. Christopher Barry also directs it well it slowly builds up, Ian very worried, and the shot of the Daleks deliberately hiding works very well. The final shot of Temmosus dead combined with the incidental music shows the tragedy that has just occurred. Ian is very good here he tries to save the Thals and understands the Daleks completely they have a dislike for the unlike and will never be successfully reasoned with. Another great moment is when the crew act as an effective team for the first time in the series in their cell all help to disable the Dalek and the audience sees for the first time a glimpse of the creature inside the casing. The Doctor and Ians faces express more than words when the top of the Dalek is lifted.
The Thals themselves are not quite as successful. Alydon and Ganatus are passable, but Dyoni and Antodus are rather embarrassing. They work best as Terry Nations expression of the limits of pacifism when faced with fascism (the Daleks) they must fight or perish. Barbara and the Doctors decision here to simply use them to retrieve the fluid link is rather worrying but again Ian shines and shows it is a matter of conscience and morality as well as practicalities. The subsequent journey through the swamp and the mountains has a touch of Jules Verne about it and makes the last three episodes quite entertaining (The Ordeal having the first literal cliffhanger in the series!). However Barbara lets the side down a bit when she tries to help Ganatus she loses her grip on the rope and she is rather stupid attempting to go round the rock face backwards. Her romance with Ganatus simply doesn't work and the line Shes just a child! to Ian about Susan may be caring but just sounds patronising.
Pace wise the story is rather slow in places, especially with Susans long trip to the TARDIS and back, but it picks up in the second half. The climax is disappointing (Kristas pushing a Dalek into a console) but is preceded by some good scenes, especially the Doctors lines Thats sheer murder! and This senseless, evil killing! His remarks at the end that he never gives advice are rather odd though surely he gives more advice than anyone and follows this line by giving advice!
The Doctors character is still a little cold. He happily fools the others about needing mercury though Hartnell does this so well that I am rather on his side. The Hmms! that he later utters so much are also not that evident here, proof surely that Hartnell used these mutters intentionally. His character is still acerbic and this comes to the foreground in the next story