It's the 5.8ghz model, the WS50. Plastic but feels as sturdy as you'd expect. Latency entirely unnoticeable (to me, others latency sensitivity may vary) bought (new) from ebay seller for just over 30 quid, arrived after a few days.
I've been using it on and off for three days now and the battery shows no sign of dying. In a direct comparison with a quality cable there was no discernable difference in sound quality.
I paired it with a line 6 g75, bug to pedal board, line 6 from pedal board to amp and the latency was there, no question, but the actual playing experience was like using a very, very small amount of echo.
Playing live it would be as good as unnoticeable. Again, other people's sensitivity to latency varies. After a lifetime of gigging under all manner of different circumstances I've grown a fairly rugged shell and so minor niggles don't bother me in the least. When you've lost all sound on stage and are playing to what you can make of the front of house until the guys get it sorted, then you can talk about latency.
Anyway, my very early take is that this is the best bang for your buck available, simply because it works, costs less than a pack of strings, and above all you are out of the 2.4ghz traffic jam.