After the first few uses in the rain I would summarise as follows: -
Comfortable enough that you don't notice it.
T-shirt arms make swinging easy - I have worn it over just a thin collarless shirt (it has a T itself to make that acceptable), over a long sleeve medium thickness top (came 6th of 40 so that tells you something). on its own (won that fourball matchplay so again...).
Does well against the rain - obviously only for the parts of you it's on.
Great bit of kit - so far (4 outings).
