bought this jacket to guide this summer in Maine. very comfortable through the shoulders because of the design of the straps (only downside is that on warmer day I get the weirdest tanlines). it allows great range of motion, and has just enough storage in the pocket for a couple energy bars or a ziploc with my keys in it, which are the only things I ever have in/on the vest other than the river knife on the lash tab and a whistle tied to the lanyard hole. speaking of the knife, my one (very) minor gripe with the vest is that the placement of the lash tab can make it a little bit more difficult to draw a rescue knife than it is on other vests, where the lash tab is usually higher on the chest.
this being neoprene, breathability kind of doesn't exist. if you're lucky enough to have a drysuit, you're usually better off wearing standard outdoor baselayers that are wool or fleece underneath and layering more wool and fleece on top as it gets colder.