I've only had a chance to use the jacket a couple times now but overall it seems good so far. Fit is definitely slimmer, I'm 5'11 and 125 lbs and a small fits me perfectly. I've used it as a wind jacket over a short sleeve wool jersey in 52 degree weather and was comfortably warm. I also used it in a light rain storm but nothing near downpour to test the actual water proofness of the material. The jacket is very lightweight and packs down small into one pocket on a jersey which is nice. Zipper works both ways so you can vent from the bottom.
The only gripe I have, and it's partially my fault, is the wrists fit large on me so a headwind tends to get up in the jacket and fills the jacket behind my shoulders. Some vents would probably solve the problem.