This one seemed slightly harder than usual, too, just like yesterday, but it might have been the fact that both of us were nodding off as we tried to fill in the answers last night. We tend to work from top to bottom, so we had no idea what was going on with the theme until we got the oddly self-referencial 56A: Four units, in 56-Across (BATTLESHIP). After that, the puzzle got a lot easier, as the other theme answers became immediately obvious. I like the nod to the classic game, and in the end it seemed just about right for an early-week puzzle.
I wasn't aware, or didn't remember, that a POLYP was a 27A: Coral producer. I guess I'll try to think of beautiful coral reefs from now one when I hear that word. (Honestly, I didn't like seeing it in the grid and I don't like writing it in the review, but there it is.) (Ahh... beautiful tropical fish and lovely coral...)
And speaking of things I dislike, I generally don't care for quotation mark clues, such as 22A: "You can count on me" (WILLDO) and 40A: "Wowzers" (GOSH). Not that there's anything (terribly) wrong with them. I'm just stating a personal preference. I prefer question mark clues, like 34D: One whose success is well-earned? (OILTYCOON). That's a damn fine clue. Unfortunately, the other question mark clue today is LIPO (19D: Plan for losers, informally?) which makes a particularly disagreeable crossing with the aforementioned P-word.
I thought SETTS (44A: Small paving stones) was a tad obscure, and ONETEN (52A: Early afternoon time) is just plain strange. Bad? Maybe. Especially when followed by NOS (54A: What horizontal head shakes signify). Shouldn't it be "noes" if you're going to use it at all?
I don't know... it wasn't terrible. I loved PETRUCHIO (2D: Kate's groom in "The Taming of the Shrew") and NEPTUNE (25D: Roman god of horses) and MARCH (24D: It was originally first on the Roman calendar) were interesting. And, as I said, the theme was good. Just a little uneven, that's all.