When in doubt, take out everything that you're not a hundred percent sure of. I struggled with the SW corner for the longest time because I forgot this piece of advice. I was so convinced that RIttEr was correct for 43D: German chocolate brand (RIESEN) that I was ready to give up on POSIES and OCTAD. Finally, I took it out, and the corner fell. Turns out the chocolate manufacturer has been around since the 1930s.
This is a lively themeless with some things I didn't love. It's centered around HATERSGONNAHATE, which was not difficult to get. I feel like we've seen it not that long ago. It's still fresh feeling, however.
I had my entry with YALE and IWILL. 31A: Roman leader? (GRECO) followed, and then I saw that ___SPICE would fit in at 4D: Jamaican jerk chicken seasoning (ALLSPICE). I've never heard of NESSES (19A: Promontories), but it's the only glue in the NW corner.
1A: Surf stuff (SPRAY) is okay. I don't love the clue, and the answer is relatively straightforward. I give it a C+. I also can hear the cries of anger at 20D: Devil or bear lead-in (SHE), so perhaps that could have been clued better.
Although I had the 15-letter answer across the middle, I had to restart in the SE as I could not get 27D: Mass master (JSBACH) from _BA__. Good to see him in the grid. He is probably the greatest musical genius in the history of Western music, although I'm sure others have their opinions on that point. Still the pair of 80s-90s TV clues were gimmes, so with WILLIS over NILES over INUSE, that section was not as hard as it could have been. I've never heard of MARCELLUS, but it was definitely inferable by the rules of Latin.
I enjoyed 35D: Still the most? (STEADIEST). I'm not sure about also having 21A: What most adjectives end in? (EST) in the same grid. It seems like duplication of part of speech as well as the same pun. On the same note, as it were, I'm not fond of ANN two answers over from ANAS, as well as the latter four answers over from another "Santa ____" answer (CLARA), especially as both the latter are proper names in Spanish.
I had a little difficulty in the NE, only because I'd put ARIa in without a second thought. ESSaX looked wrong. And I suppose because Die Fledermaus is in German, I suppose we can allow ARIE. But really. It's an aria.
My favorite clue-answer pair is 29D: Force on a nut (TORQUE). I like the opportunity to go the wrong way in the clue, and the loveliness of the actual answer, which sits so nicely in the grid.