I'm keen to use it in the future, but my favourite microcontrollers are always listed as out of stock, I the attiny1617 is quite a recent part but it's showing zero stock, as are the related (possibly compatible with my firmware, with some mods) parts. The microcontroller is the main thing I want to be installed.
I did try going through their interface and managed to reach a plausible looking preview (minus the unavailable microcontroller) with the other parts present, and only a few parts installed backwards.
Also I want to make very tiny boards which are too small for their smt service, which means I either extend the board with removable (waste) panel, or I panelise two boards myself, which complicates matters.
But if it works, and from what I've heard, it's basically unbeatable.