It wasn't nearly as kinky or freaky as I'd feared it would be, even with the sex in dolphin form. It was always made so clear that even as dolphins, they were still very much George and Patrick. That helped mitigate the bestiality/squick factor for me as much as for Martin. And the threesome was well done and made clear that it worked better that way than in any possible twosome combination.
So it turned out to be a surprisingly sweet story about lonely people finding each other, connecting, developing friendships, etc. - not just the three MCs, but also wonderful secondary characters who had great platonic relationships with them all. The dolphin aspects were a fun and interesting extra layer atop the solid foundation of a wonderful, very British story.