Mark Halladawrote a review of Castelli Idro Jacket - Men's on February 16, 2018
Familiarity: I've used it several times
This thing is crazy light, sheds water like a duck, and does indeed shake dry.
I have worn it riding in a light drizzle, in 46F and windy, and in the shower. (Yeah, I wanted to see just how waterproof it is). It passed all three tests. In particular I think this would be a good emergency wind, cold or rain garment; on the forty-six degree day it was windy (14 mph) and wet: I wore a Craft long base layer, short-sleeved jersey and the Idro-- and it was plenty. The Idro is easily packable into a jersey pocket.
A nice touch is the zippered slash rear access in just the right spot to reach your jersey's right rear and center pockets; it also can be opened to allow a little through-flow of air to prevent ballooning if you unzip part-way in front.
A word on sizing. I'm 6'1" 182 and were I thirty years younger than my sixty I would be fretting about not being closer to the 175 that I weighed, well, thirty years ago. As it is, for Castelli race-cut jerseys I tend to fall somewhere between Large and XL so I bought this in XXL so as to be able to layer freely. The XXL on me accommodated a winter long-sleeved base layer and jersey fairly easily with a little bit of flapping but not much.