Some great feature entries. I particularly enjoyed the juxtaposition of SKIMOBILE / TEN SPEEDS — it's neat when constructors can relate adjacent answers. Tiny feat of magic.
HEBREW CALENDAR was a treat, a colorful answer in a rarely-used grid slot. It's incredibly tough to weave in a 14-letter answer, one of the most inconvenient lengths for constructors. Far, far from an AMATEURISH result.

People often ask me what differentiates a Friday and a Saturday themeless. Will's short answer is that Saturday should be harder than Friday, simple as that. Only it's not so simple. There are so many different ways of turning up the difficulty dial. The most straightforward way is to make clues esoterically challenging, but that's usually not a fun solving experience.
Another way is to work in tough entries that will only be familiar to solving subgroups. The risk is that while you make the puzzle memorable, even standout, to those folks, you might cause broader solving angst.
OUROBOROS is a prime example. A few years ago, I had a puzzle in the Chronicle of Higher Education, based on the legend that the BENZENE ring — one of the most important and curious structures in organic chemistry — was imagined when August Kekule dreamed of OUROBOROS eating his tail. Now that's a story! It's fascinating trivia, but I can see how it could alienate people struggling with the strange sequence of letters standing in the way of their perfect crossword solve.
KAZAAM. I'm a big NBA fan, so I knew this right off the top. Talk about Shaqtin' a Fool! Again, if you didn't know this and guessed KASAAM / SAPATISTA as a crossing, I'd be sympathetic.
GALOP. Famed for its pluralized inclusion in Rex Parker's NYT debut crossword, I've come to change my mind about this one. When I initially solved Rex's puzzle, the inclusion of a single, bizarre word which affected my ability to accurately finish, was striking. Now that I've seen it a few times, it doesn't feel as icky. Perhaps even interesting. Perhaps.
ARTEL. Infrequently used this decade in the NYT; it's a tough term that could bring a huge sense of triumph to history wonks. It has the potential to alienate, though.
Kameron is known for his avant-garde grid designs, often aesthetically striking, and his upscale vocabulary / knowledge base. The latter was on display today. I was fortunate to finish this one with no errors. (Alas, Jim wasn't so lucky).