been out for a 5 hour walk in heavy rain followed by passing showers. I wore ontop an eVent peak cap, the Mica, and a Cambia base. On lower some shorts and OMM Kamleika pants, and Keen sandles over Sealskin socks.
After walking for 2 hours into the wind and rain I went indoors to find out where moisture was heading. I could feel a little cool patch under my right ear / upper-shoulder. There was a damp patch essentially over the right shoulder. I don't think that was the Mica failing but rain blowing in through the gap in the hood made by the cap. If I wasn't wearing the cap likely I would have had less of a gap, the peak cap was shielding rain from getting under the chin so no cap may have meant I would have been damp above the sturnum. I was generally dry, none of the overall wetness you get from bad-breathability fabrics. So I'd say yes waterproof, yes very breathable. The rain I'd say was Lake District wet for about an hour windy driving on my front-right side where the damp was.
I then kept wearing as the heavy rain changed to passing showers, the Mica was beading very well and dried quickly. I then kept it zipped up as I felt too-warm to need it, to force up internal humidity to see how the breathability would sustain, the inside fabric remained dry even though I felt I needed to take the Mica off to cool. So yes, quite breathable.
Overall, on just one outing, it works as advertised, a waterproof very breathable, lightweight simple jacket. I need to tune what I wear around the neck, i.e. not wear a wide-brimmed cap and probably use a Buff to keep my hair off the fabric (to help maintain the fabric breathability). The best hood on any shell I have owned is the Rab Drillium, that should be copied by many as it solves the issue of keeping water outside. Alternatively, use an umbrella!
So a few small niggles are that I can't cinch the sleeves up tight, there is missing enough velcro to wrap tightly, but that's easy to solve with some velcro and glue. It is a tad too tight across the chest (Medium size) but I'm fairly fit from cycling a lot the 2 weeks prior, and I know that adds to chest size so I'm probably close to my maximum chest size at the moment, when less-fit I'll likely get more space.
It is showing up the worst part of my kit-list, my OMM Kamleika is showing up its relative lack of breathability, when I removed them they were wet inside from my sweat, the Mica being dry. I also need to find a better solution to Sealskinz and Keen sandles, my feet was squashing in water most of the time, cold and on removing the socks damp all around the toes. I will run my Sealskinz with tap water to see if they're leaking, my suspicion is Sealskinz awful breathability when in a puddle (inside the sandles). My boots are bust (cracked sole) if you're wondering why sandles.
Happy to now rely on the Mica as a warm-weather waterproof to pack! 
