Frannie here. Horace is out saving the world. Before he left, when I asked what he thought of the puzzle, he said, "meh." I had to wonder what I thought of the puzzle because we did it together after getting home late from the bar again last night. I think I dozed off around BEATSME, but came back in time for 57A, the big revealer: Phrase that defines (and describes) the other theme answers, IHAVENOCLUE. The parenthetical (and describes) makes it funny. My favorite of the theme answers is HELLIFIKNOW (18A). Starting with HELL makes it funny. 44A. Mark one's words? (EDIT) is also funny.
14A. Bottom line? (HEM), a faux financial clue, was funny, but 41A. Money spent (OUTGO), an actual financial clue, was not. I found the inclusion of both OTO (12D. Ear-related prefix) and OTOE (45A. Siouan tribesman) odd, too.
36D. Fred and Barney's time (STONEAGE) brought me back, so to speak, as did 65A. Nancy Drew creator Carolyn (KEENE), and 50D. Don of "Trading Places" (AMECHE).
I'm going to guess that Huyguens enjoyed 11D. They have umbras and penumbras (SUNSPOTS), but that he probably would have enjoyed it more if it had focused on the 'bras' instead. :)
I fear our loyal readers would not be satisfied without a review of interesting fill. In this category, I would include 1D. CHAMPS, 20A. MYRIAD, 49D. ERSATZ, and 53D. ARETE. Not too much fill fell into the poor category, but there were a few such as 34D. GOOD, 7D. MIL, and 39D. MUS.