Boy, the SE quadrant took me several minutes at the end of this. I did not know KIGALI (50D: Capital of Rwanda), CLAMUP (49D: Stop talking) took some crosses, and the excellent SPANKS (51D: Hits bottom) was not immediately obvious. SOCKS (48A: Low pair?), too, was very tricky! Also, "Louvre" fit into the six boxes clued by 47D: Parisian palace (ELYSEE), so that didn't help… but in the end, it all got filled in, and as I've said many times, I appreciate any extra challenge early in the week, so it's all good.
Not so good, for me anyway, was the theme. POWERCOUPLE (36A: Beyoncé and Jay Z, e.g. … or a hint to 17-, 30-, 44-, and 61-Across)? SUPERSTAR (17A: Luminary among luminaries) is a "power couple?" I guess maybe it's because the two parts of that compound word, when "coupled" become "powerful?" Is a SUPERSTAR powerful? Is a HIGHHORSE (44A: Snooty attitude) (nice!)? No… wait… it's another one of those "both parts can be paired with "power" themes. Sorry for the false alarm. "Superpower," "star power," "high power," "horsepower," … Much better.
After a terrible start (ANAL (1A: ____-retentive) (enough already!), there is lots of good fill today: NAUSEA (2D: Feeling after a roller coaster ride), SCRAPS (9D: Leftovers), NOUGAT (10D: Candy bar filling) (gross!), CAPABLE (25A: Competent) (bonus theme material?), PISTOL (38D: Energetic sort), HECKLE (45D: Shout "Ref, are you blind?!," e.g.), KOOKS (58A: Wackos), and more. That's all good, and the theme (now that I get it) is fine, and the elements of the theme are all pretty good. Let's call it good.