After three days of use, initial findings:
Goodies: good face pockets, apparent solidity of the whole, intelligent opening transparent pocket (via a closure), good overall stability.
Cons: too long tie from the bracket (relative to the diameter of my jib) and Surface "velvet" insufficient compared to the surface "hook" (one lap around the stem completely covering the "velvet" should be "hacking" and make two turns tethered to effectively use the hook and loop fastener), transparent pocket a bit tight for my phone diameter of 143 x 76.9 x 9.6 mm.
Especially, my knees rub against the side pockets when I pedal. Yet I am not large (1.77 m) and my bike has a frame 50 cm (size maybe slightly too small for my size, but recommended by the seller of the bike). I wait to see if this problem is actually crippling in the long term.
For the price, however, the product is very correct!