If its the one in my loft waiting for warm spring/summer days then I love it.
Slide in a back protector for your own security rather than the foam item. Certainly wouldn't like to take a long slide in it but I use it through the city/beyond and have never been disappointed as it keeps me cool and whilst we are on the subject the trousers comfiest I've ever worn. Best not to get caught in the rain, but frankly in August a wet ride is more fun that a sweaty ride (insert sexual innuendo as you see fit)