The jacket is very light, and waterproof is excellent.

I purchased the Barfly Jacket as a rain and wind shell for my three week trip to Scotland including a ride around the North Coast 500. I used the jacket every day of the ride, through wind, heavy rains, hail and cold days. It held up to the ride and weather without any problems. I was able to layer it over my Klim Marrakesh jacket and thermals. I ordered my normal size (medium) and had no restrictions on movement, even over the other layers. The drawstring made it easy to adjust the roominess without letting it billow in the wind. The bright red color combination made me stand out on the ride since most riders in the UK seem unfamiliar with color concepts other than muted shades like brown, black or green. I also received several inquiries and compliments. After the ride, the Barfly also doubled as rain/wind shell on several hikes around Isle of Skye. During the downpours my pants were soaked but my upper body was completely protected from the external elements. The biggest pros were the reliability of the design, the ability to easily layer and adjust the sizing, and the packability of the light shell. Don’t confuse this jacket with a highly-ventilated hiking or riding jacket. The waterproof lining reasonably prevents condensation but you will sweat if you exert yourself like on a strenuous hike. I definitely suggest the Barfly jacket if you’re looking for a lightweight water and windproof shell.

you can feel the quality in the material and the way it's put together. Barely takes any room when packed.
Highly recommend.

1 star down as it's almost not possible to fully close the zip .
I should be easily just zip up the zipper to fully close it , unfortunately the little ''pocket'' in the collar always is on the way on the zipper and block it.
To close it I have to fold this ''pocket' out of the way first , close the zip , then fold that ''pocket back '' . Seriously this kind of hassle should not be happening !

Apart above...it's truly a fantastic over-shell Jacket and I love it !
The material has a lot of stretch , I almost don't feel I wear it .
Despite no vents I don't really overheat during off road technical riding .
Material breath quite well and is not sticky inside.
This is the most comfortable rain jacket I had so far to be honest !

Additional bonus is, that you can use Barfly Jacket not only on the bike , actually I use this Jacket almost every time is raining and I am going out of home .
The hood has a really good shape and serve very well during walking under heavy rain .
I really like the Red Rust color which isn't bright red , actually it's quite toned and looks really classy .
Its everything I can say for now after just a few weeks of using it.

Durability update will follow after few months of use.

As per sizing:
I mostly use Medium American sized Jackets or Large European sized Jackets .
I purchased Medium Barfly Jacket and for me it works very well .
Because of the stretch materials used , it fit comfortable over separate Leat 5.5 armour , Jackaloft Jacket and my mesh Jacket .
When I wear it over separate armour and Jersay only, it is not excessively big . It's nice and snug , comfortable in every combination . Love it !

Can recommend for anybody !

Ce que j’aime le plus c’est la légèreté du manteau, je dirais que tu es bien dedans même au soleil jusqu’à environ 25 dégrée Celcius. Je le porte avec un mid layer arcteryx atom lt et c’est super si il fait un peu plus froid . Coupe la pluie a 100%. Le tissu est extensible ce que j’adore. Je mesure 6 pied 3 pouce et pèse 255 lbs et le xxl était bien pour moi . Le xl était trop petit j’ai dut le retourner et commander le xxl.
Super manteau le capuchon ne pogne pas trop dans le vent non plus. J’ai l’impression d’être entre deux size car le xxl est pas mal plus grand que le xl donc le manteau quand je roule pogne dans le vent et gonfle du dos, je ne peut pas rouler avec les poignet lousse je doit vraiment les serrer pour ne pas avoir d’air qui rentre à l’intérieur sinon je deviens comme un parachute. Mais somme toute je suis super content et je porte le manteau souvent. J’ai également le pantalon barfly que j’adore également.