Absolutely recommendable. I have a Ryzen 9 3900X installed. The BIOS is awesome for me. I have already updated it to version 2.50. Self-explanatory in the BIOS. Format the stick to FAT32 beforehand. I only run overclocking very discreetly, so I can't speak for people who want to squeeze out the last bit of performance. But the PC runs like this.
Good A-Data RAM and Samsung M.2 970Pro SSD. Awesome. The highlight of the board for me was the M.2 WiFi slot. I installed an Intel network adapter, which is more commonly found in laptops. WiFi is faster than before and there's no stupid antenna on the outside. Here you have to be careful that you order the 9520 (around 30 Stutz), NOT the 9560, as this only works with Intel chipset.
I have a Geforce 1050 Graka in it. With m-ATX it will probably be difficult to upgrade due to the thickness of most cards.
For me only Asrock.

Greetings

Is it recommended to use this motherboard with a Ryzen 9 3950x?
I can't report anything detrimental. All installed components work flawlessly.

I have no problems with a 3700x except that the mainboard gave up the ghost after about 1 week and Digitec needed at least 1.5 months to replace it.
The 3950x is supported according to Asrock.com.
The mainboard is probably the only matx board with 4 DDR ram slots. I have 2x 32GB in it and will buy another 64GB.

Unfortunately, the part is junk. I had extreme problems with the XMP profile. Everything above 3400Mhz led to regular crashes and BIOS resets. I also had to turn up the voltage for the 3900X because it sometimes didn't keep up with the power supply at the beginning (cold start with power peek). I would have returned it a long time ago if it wasn't the only mATX with X570 chipset on the market with 2 M.2 connectors. (There are only 2 worldwide...)