I've been using this board now for a week or so. I'm sure I'll have more to say about it with longer-term usage, but it seems very familiar to anyone who's used one of the ASRock Rack boards in the past - particularly the smaller, "quirkier" ones.
There have been two minor "snags" during the build that have annoyed me:
<rant>
They used a Molex Nano-fit connector for the ATX12V and included a converter from Min-fit x24 to Nano-fit x4 in the box. This wouldn't otherwise be a problem, but the adapter is short and the wide, x24 connector obstructs airflow off the CPU cooler. I will probably try to wire up a more aerodynamic adapter at some point by using a short pigtail from Nano-fit x4 to Mini-fit x4, then a longer run at higher wire gage back to the PSU for the 24 pin connector.
The second niggle is the right-angle header for the USB front-panel, way down at the bottom center of the board. Right-angle at the _right_ side of the board is ideal - that typically faces the front of a chassis. Being so far from the front of the chassis, I needed to use a flexible extension to provide enough cable relief to plug a cable in without ripping the header off the board, and even _more_ relief to clear the back of the card I have in the bottom-most slot.
</rant>
I would still buy the board, and it's the best fit for my needs, but like all ASRock Rack boards I've used, it has some "special" design ideas to get so much functionality in such a small footprint.