The Dalek Invasion of Earth is good - in fact, the first three episodes are excellent, with the Dalek coming out of the river at the end of episode one, and episode three a real high point, with the scenes of the Daleks in London, wandering past Westminster, congregating in Trafalgar Square, and patrolling the Albert Memorial (having obviously somehow got up the steps) particularly effective. That is also the episode where Susan tells David of her feeling of dislocation: "I never felt that there was any time or place that I belonged to. I’ve never had any real identity." And the incidental music is great - I hadn't heard of the composer Francis Chagrin before but he was apparently a well known film composer; shall look out for his other work. There is a real feeling of occupied Europe resisting the Nazis (and I write this in a village which experienced that directly rather than just in the cinema).
It is a bit let down by episode four, with no Doctor in sight and the rather rubber-suited Slyther, and the Daleks' actual plan when revealed stretches our suspension of disbelief. But the pace is kept up (especially by Jacqueline Hill as Barbara).
And finally the departure of Susan. Beautifully done, the first time that a member of the regular cast had left the show. "Just go forward in all your beliefs, and prove to me that I am not mistaken in mine," says the Doctor, promising to return, but we know he never will.