I liked this one just fine. Simple theme, TOOLBOX (40A: Handyman's tote), with four symmetrical tens pinwheeling around the grid, each ending with a tool name. Nice.
I don't know Nicholas Gage or his memoir (ELENI), and SEAEEL (20A: Sushi fish) is a new one, too, at least to me. I suppose they're different from river and/or lake eels? But isn't "eel" enough? HAHAS (43A: Big laughs) seem a little more like regular laughs (guffaws? yucks? howls?) but, well, that's fine. All over the place there's crosswordsy-type stuff - OBIS, ILIE, OTT, EKED, STEN, SSTS, ELLS, SRTA, but, well, it's Monday, and I'm still going to ENDON (24A: ____ a happy note).
I liked PROXY (26D: Authorized substitute) and STIFFS (48D: Doesn't leave a tip), and you know what? I even liked TENKS (13D: Marathon warm-up races), although I think you'll need a little more than a 10K before you run a marathon.