Very neat concept today, not sure if I would have ever thought it up: thirteen words in a progression, starting with A, B, C... and ending in Z, Y, X, ... (the appropriate letters are highlighted in the answer grid below). Sort of a dual alphabetic progression, the starting letters going forward, the ending letters going backward.
A perfect start to it, A TO Z being the ideal revealer at 1-across. Often times, revealers at 1-across can come across as deflationary, sort of giving away the puzzle even before the solver starts. So I like the way David/Will presented the puzzle. It's not ideal having to read a note even before you begin solving, but I think it was a reasonable solution.
Extremely tough from a construction standpoint. Not only must you incorporate 13 theme answers, but they all have to follow a particular alphabetic constraint. It did feel a little odd that so many starred clues were for short answers, but it would be near impossible to have your themers be the longest answers in a feat like today's.
As with all audacious constructions, signs of stress pop up in the grid. Once you lock in the (slightly made-up feeling) EX-GOV, FONDU, and ICIER, there's the MTGE, GENL, SLUE pile-up in the middle. Not ideal from a smoothness standpoint, but almost necessary given the high constraints.
Another shoot-for-the-moon decision was to use GARMENT DISTRICT instead of another short answer such as GET IT? or GLOAT or even GET. I have a feeling that would have smoothed things out in the west and east (where HIKES and FONDU overlap GARMENT DISTRICT) but it is pretty impressive to have that grid-spanner as a theme entry. Same goes with CHATTERBOX (the more boring CAR WAX, CONVEX, etc. could have eliminated the old-timey ONERS plus ERI, ENORM, ORONO) and KARATE CHOP (KIDNAP, KISS UP, etc.).
All in all, a clever idea and a high-reaching construction with some trade-offs in solving smoothness.