I've just received the board in the mail and haven't had a chance to get it fired up, but looking forward to doing so. The boards arrived quickly - especially considering it was an international shipment.
The seller offered ahead of time to burn on some firmware that should enable me to get up and going very quickly, so that is much appreciated! 5 stars for that. Build quality looks good, and it looks like the design of the board was done with reasonable care.
I took off one star for documentation, since none was included with the boards, although there is detail online. A packing slip with some basics, like the URL for additional references, would be ideal. By the time the boards arrived, I had to Google for the Tindie page to find the details. The URL silkscreened on the board just links to a page with some basic info, but nothing about the board itself.
I really like the idea of using common industry RFID readers as IoT devices, as it lets you integrate door control into a larger universe of logical IT endpoints. Glad to see someone pursuing this as well!