Fun puzzle, love a good themeless! I really vibed with your fill here, especially VALHALLA, and I enjoyed a lot of the cluing angles, with my favorites probably being 1A and 22A. Thought some of the clues could have used question marks though (notably 23A). Good stuff!
1A and 22A are top-notch clues. The clue for SERENA is a classic and often appears without the question mark, especially in hard late-week themelesses.
Fun puzzle, thanks! The title Terrapin kicked in my long addiction to the Grateful Dead, so I was looking for something related to them. Then I noticed "Themeless" so I just turned on a concert with Terrapin Station in it and all was well.