I learned a new phrase today - CAMELCASE (28A: Style of "iPhone" or "eBay," typographically). A word written in CAMELCASE can start with either a capital or a lower-case letter, but every new word starts with a capital letter and no space. So "MySpace" would also be an example of it. Interesting. How have I not heard of that before?
Anyhoo, CAMELCASE is just one of four theme answers, the first word of which can be put after JOE to make two advertising names, Joe Boxer and Joe Camel, and two common(ish) epithets, Joe Cool and Joe Blow.
As I was filling in answers today it felt like there were too many stale entires like APER, ETUI, ALAR, URAL, INCA, ERAS, OPART, ABUT, OREO, TARA, LARA, ADDER, CANER, ENDER...
1A: "That's hilarious!" (HAHA) is a C. I did enjoy DUENORTH (38D: 0 degrees, on a compass), and I chuckled being reminded of GASOHOL (44D: Low-ethanol fuel blend). Does anybody still say that? They're now called "E-something" right? "E-10?" "E-25?" I think we saw that more when we were buying gas in Europe.
I'm happy about learning a new term, but overall I didn't love it.