I've used a couple of them, without the sound jacks, though. The first one was a rugged box with sturdy buttons for four monitors plus daisy chain mode, modular with detachable cables. I sold it to a small company who still use it. The next one was a smaller one by Aten with two fixed cable sets. It only works with a hot key on the keyboard. The only complain I have is that there's something wrong with the other monitor cable, the picture sometimes lacks red. A fellow ordered one with USB, haven't heard him complain.
My advice: Get one with flexible silicon cables, exchangeable if possible. Plastic cored stiff cables always seem to bend in the wrong direction, making a terrible heap of spaghetti. OTOH dust bunnies seem to like it, makes them feel safe I guess...