Part continuation from the prior two stories featuring the Master, part regeneration story, this particular serial doesn't really have an "adventure" of its own per se...but that being said, its a pretty good one. It was the fourth serial recorded for the season, so Peter Davison already had his portrayal set, which made the transition smoother in my opinion as he goes through all the instability of his new regeneration.
As far as special notes about this one, its the first time there's a pre-credits scene, as the regeneration is replayed before the titles...showing Peter Davison for the first time. In the end credits, this is the first time that the Doctor's role is credited as "The Doctor" instead of "Doctor Who" as it had been since the beginning. This would continue until the end of the original series' run. In a minor slip of continuity, Tom Baker had worn the buccaneer boots in Logopolis, however after the regen Peter Davison is wearing the socks and shoes variation of the costume.
I really enjoy this one, and Peter slips into the role very nicely. I really enjoyed his impersonations of the previous Doctors in the first two episodes. It was a nice touch and well done. I also thought the sets and special effects realization of Castrovala itself was pretty cool, too.