Last night I started watching this, purely because I had it handy and I couldn't be bothered looking for anything else, and I suddenly remembered how much I actually really like it! It seems to be the sort of story that doesn't often show up on lists of favourites, but it really does have its moments. The chemistry between Sarah and the Doctor really gets going here, with Sarah teasing him for most of the first episode - Sarah is ultra-cute, and you can see the beginning of the sort of relationship she later has with Four, which really makes me wonder how things would have developed if Jon Pertwee hadn't left... Also, the plot is quite exciting, really, even if six episodes does seem a little long.
Anyway, I just thought I'd mention how much I've been enjoying this underappreciated story!
'Life is the most wonderful fairy tale of all!' - Hans Christian Andersen, from What The Whole Family Said