Well, bought a pair of these pants.
To me it looks like a 2mm thick standard closed cell foam cut criss-cross like some self-inflatable mattress foams and quilted between two layers no-see-um mesh. Construction has slight stretch, is very light indeed and is not going to take lots of rough use. There's enough cuts to let air circulate a bit more than inside a windshirt. Absorbs 200gms of water after being fully submerged (roughly similar to same weight of fleece) but dries very quickly.
Used about dozen times for running and cross country skiing between -10F and 30F.
Always without any long underwear. Remarkably wide temperature range. As you start overheating, the sweat instantly evaporates from your skin. Like it should. Feels a little chilly but not really that cold. As you stop the activity they are pretty soon bone dry. There's a dramatic difference in drying speed to Powerstretch - windbreaker combination that is not bad either.
Conclusions this far:
- pretty stiff price for this simple construction with probably bad durability
- works great for cold or cool weather outings where you are going to get wet