Another good novelisation by Terrance Dicks here, and in novel form doesn't suffer from any of the special effects issues that the TV version has (going through these, it does feel like they had issues on this front in the 80s, the 60s and 70s versions didn't seem to suffer so much, but with the snake in Kinda and the Myrka here, really became more obvious).
We see the return of the Sea Devils and the Silurians here, and while similar sort of theme, is less nuanced than in prior stories, as they seem to have given up hope of peace, and so the Doctor's efforts in this regard have no chance of success, rather than little chance as prior :)
The Doctor is in good form here though I feel, able to take charge a bit more readily than at times of late, and certainly does his best. Tegan and Turlough also in pretty good form I think, Turlough showing that while a coward at heart, can be brave when needed and not fall apart, and Tegan is her normal proactive self.
The one off characters are an interesting collection, with some sad scenes, and certainly we are starting to see an increase in death count again, something more akin to the UNIT years and up to and including the horror years of the Fourth Doctor.
All round a pretty good read.