Yeah I think its similar to skins, it feels like wearing a tight shirt made of silk or something(not in a gay way), it's pretty hot in the garage I train in but I noticed it keeps my body at a good temp, I still sweat but its hardly as annoying as with normal or no shirt.
I only have the short sleeve version so my forearms sweat like crap compared to my chest etc. It's also got something in the fabric that seems to stop body odour completely. I'v worn it 2 days while training now and it still smells brand new.
It makes it alot easier to see definition and the shape of my chest//abs//biceps where the shirt is, when doing benchpress//flys//curls the fabric stretches with the muscle, stopping vibration. Makes me wanna get the 3 quarter pants and see what running in them is like, they are also perfectly fine to wear under clothes, I wore mine with a shirt ontop the other day and I still kept relatively cool.
I'm pretty sure the slazenger one I got is just a cheaper brand of the more expensive skins you can buy from Rebel allsports or places like that, this one was only $35.
I just did a workout before(chest//tri's//abs//bi's), I got no fan in my gym so it got pretty hot, as soon as I walked into my other room with a fan and it blew on the shirt I noticed a very cool feeling as if the shirt was absorbing the air or some crap LOL. Cooled down pretty fast.
Doesnt look too bad either: