Not a proper review, but here's one reason why I think this DVD is worth buying:
One of Patrick Troughton's gifts as an actor was to bring out the comic, eccentric qualities of the Doctor without descending into the silliness of one or two later incarnations and by the time the Krotons was shot, he'd perfected his interpretation of the character. If you like Patrick Troughton, you'll love him in 'The Krotons'.
The Krotons is an reasonably good story that is let down by some ridiculous aliens who sound vaguely South African. I'd give it a maximum of three stars, but Troughton's performance is such a joy to watch that it is worth buying the DVD just for that. There is one scene in particular, in which the Doctor and Zoe are completing puzzles for an intelligece-measuring machine, that the chemistry between Patrick Troughton and Wendy Padbury results in one of the most endearing, comic moments from the Troughton era.
This four-part story isn't as bad as 'The Space Pirates' but is nowhere near as good as 'The Faceless Ones'. There are some good performances from the supporting cast - notably the late Philip Madoc - and the premise is quite interesting, but as far as I'm concerned, I'll be buying this for the joy of seeing a digitally restored Troughton story with the added bonus of the special features.