Sweet Jacket
Just received my Arcteryx Fission SL Jacket. Super warm and lightweight! Will be perfect for the backcountry excursions and some winter camping. Now I can have one winter jacket that does it all!

The best!
My absolute favorite jacket! The fit is perfect. It doesn't stick out at all. Great warmth to weight ratio. A t-shirt and this jacket is all you will need to keep warm!

So great!
I really love this jacket.Supper warm and the interior is soft.The Gore-Tex Pro Shell is amazingly rugged. Very tough shoulders and wrists and the rip-stop style shell body is a nice touch.

Synthetic down?!?
First impressions - this is an amazing piece of work by Arc'teryx. The feel of the Fission SL reminds me of an ultralight down jacket - weighs practically nothing and feels silky smooth against your skin. The 2L ProShell outer layer is extremely thin, yet supposedly very durable. The inner lining (black version) is an odd brownish color (with a purple hue?), and looks/feels like ripstop silnylon (to which the ThermaTek insulation has apparently been laminated on the inside). Although I haven't tried it, this jacket seems to be highly compressible! Very warm. First (and only) test run was 35F with steady rain - I could have spent all day hanging out in that rain! Once I got moving on an ascent, it heated up pretty quickly and got a bit clammy inside. Pit zips are a godsend, but it was difficult to dry out (taking a break to cool down might have worked). Complaints - velcro cuff closures are cut strangely and can poke out uncomfortably unless properly adjusted (maybe there's a purpose?). Hand pockets are minimally insulated (most/all the insulation on mine seems to be behind the pocket), but they're windproof and pretty warm so far. Collar is not independent of the hood (a feature common to many Arc'teryx jackets), but this is a minimalist piece, so to be expected. Fit appears to be normal for Arc'teryx, a bit on the puffy side, but considering the warmth it's nothing really. Plenty of winter testing yet to be done, but so far - amazing performance considering there doesn't seem to be much to it!!

Nice!!!!!!!!
This jacket is incredible. Yesterday I was out in a 30 mph, 28 degree wind and driving snow. I was wearing a flannel shirt and the Fission SL. Warm and toasty and yet it is so light and well-cut that it feels like you are wearing nothing at all. I have three other Arcteryx jackets. Two of them are deeply disappointing because the sleeves are lined with high-friction fabric that makes them hard to put on and take off. The sleeves also constrain your movements while you wear the jacket. Beware!