Where to begin? How about at 1A: Artificial eyelashes, informally (FALSIES) (C). To me, FALSIES means an entirely different set of artificial items, and I am unaware of the term being popularly used SOEVER [SIC] other than that. HAHAHHAHAHHAAAA "So ever...." Terrible. And here's another terrible thing, BASSSAX (26D: Big wind). I offer this from Wikipedia: "The bass saxophone is not commonly used in any music." What's next? Tubax?
On the other hand, I enjoyed the clues for ELEVEN (31A: It may represent November), ALIASES (40D: Things you can assume), and DERRIERE (36D: Behind). BARTABS (8A: Things with round numbers?) is cute if you don't think about it too much. ABSOLUT (12D: Screwdriver selection) is better, but I prefer Finlandia.
So overall I found it ERRATIC. I appreciate that Mr. Steinberg is getting in some more youthful fill like CHILLAX, DUBSTEP, BELIEBER, and ECOCIDE. And I guess that since it's Friday I can't argue too much with some of the more specific fact-answers like ENID (35A: Seat of Oklahoma's Garfield County) (You don't say.), RUSS (10D: Bygone sportscaster Hodges), and REYES (25A: Point ____, Calif.). It wasn't for me, but I'm betting others ended up liking it. Here's hoping so.