This PoE hat does exactly what it is supposed to do (power the Pi over PoE), however a few details makes it unpractical. The seller uses non stacking headers (that he has cut himself from longer strips) which prevent this HAT to be used with additional HAT (the PoE needs to be at the bottom of the stack). I did not test the ability to provide stable power under high load.
I ordered two of those two weeks ago. The hats were delivered in a bubble enveloppe. When I opened this bubble enveloppe, both boards were broken on the weak point (will post pictures soon) and the soldered addon was bent out of alignment.
I'm not sure if this happened at the customs or during shipping, but the bubble enveloppe sure isn't a good choice for this kind of fragile board. A box is more handy as it can be opened and closed with tape while still protecting the product. Also combining foam with bubbles is more efficient than using bubbles only :-)
I'l test those cards this evening to see if the bent pins are still connected, and if I can still manage to attach it to my raspberry py. I'll post pics and update this review with the results, but I strongly recommend Canerdurmusoglu provides a better packaging and updates the product description so every further buyer knows about it.
The multiplexer has never work for me. I tried the multiplexer and I think than I accidentally do a short circuit that has burn the chip and one of my Pi camera (the second was correct). It seem like normal than it's doesn't work, as we can see on their GitHib in the "issues" where only 4 of them has been resolved and a lot of peoples than have the same troubles. A person have also open a other GitHub to try to do reverse engineering to see why it's doesn't work. Seriously, don't buy this and chose a other method to have multiple camera, like using a other type of board (like the "Raspberry Pi Compute Module I/O Board" of Adafruit) or use multiple USB/IP camera or any other type of camera. Personally, I choose to have one Pi Camera and multiple USB camera for my stereo system and it work very easily without any problem.