Very satisfied with the product and LDLC, not with the delivery
Very good screen, it's a real pleasure to have 2 17" screens in 1, and with 5k x 2k resolution.
In practice, I'm using it a little below its maximum capacity (but still at 3440 x 1920) because of my 2 laptops, which have a limited graphics card, but the quality is already excellent.
The sound isn't extraordinary, but it's fine for videoconferencing or watching a video from time to time.
The screen can be used in vertical mode (I've got a special heavy screen desk arm that lets you do that), but it does look really big and high ;-).
So overall I'm delighted with my purchase. On the other hand, delivery was a disaster, but that's not the fault of LDLC, who helped me with the formalities and even refunded my delivery costs in the end.