Man, I loved this one! I got in quickly with STINKSTANKSTUNK (17A: "The three words that describe" the Grinch, in song), and ran from there.
I loved the cluing here, especially 10D: What irregulars go for (LESS), 23D: Otto's preceder (SETTE) (Italian. You were thinking rulers, like me, right?), 35A: Subtractions from the division? (AWOLS), 16D: Heeded a herald, say (HARKED), and many others. I tried "STUCKTOtheRIBS" for "12D: Was satisfying, as a hearty meal", but when that didn't fit, I tried the old crossword standby STUCKTOONESRIBS and what do you know, it stuck!
The fifteens were all decent, the earlier "ones" comment notwithstanding. Again, I loved the cluing on those, too - 44A: Not discouraging feedback (OPENTOCRITICISM), 2D: One doing the rounds very quickly (AUTOMATICWEAPON), and 3D: Something to level with (TRINITROTOLUENE). Good ol' TNT. You don't see it written out all that much, but it'll level just about anything you put it near. Hah!
It had some odd stuff that I had never heard of (EDELS, OHKAY, DAMES), but they didn't hold me up any, and overall, I really enjoyed it.