I've got some, and they're nice and cool - cooler than BMW Airflow trousers, which are the next coolest things I've tried. They're also comfy and the pockets are very handy. And they are nicely low key and "non-bikey" when I'm off the bike. I don't think I'd consider wearing anything else in 40 degree heat. There doesn't seem to be anything else as cool on the market.
But...I do wonder how much they compromise on safety. (I haven't crash-tested them yet.) The armour they come with is pretty useless, so I've fitted some Hein Gericke stuff - light, comfy and cheap. And I'm not sure the zip off legs are a good idea - in an accident I'd have thought the zips would give way fairly easily. I might even sew mine up.
They keep you cool by having quite a high cotton content (another safety compromise) so they breath more than Cordura trousers do. They don't have any vents. So I've been thinking about trying to make them even cooler by adding a few eyelets here and there.
If a thing is worth doing, it\'s worth doing to extremes.