Expensive but well built
I'm 5'11" and I weigh 170 pounds. I purchased the medium and it fits snug in the waist. The construction is excellent. Some reviews complained about the large hood but Arc'Teryx has built-in four methods of adjustment to cinch it down to the user's liking. I've also owned the Beta SL and for $50 more you get pit zips and a slightly longer skirt. I think it makes the Alpha significantly more versatile and worth investing $50 more over the Beta.

Great light hardshell
Absolutely, it's very useful for some easy outdoor activities. Although it 's not more excellent than Alpha SV for those severe weather, It 's lighter and easy to take, Moreover, it 's more breathable.

great jacket
Light and comfortably jacket I love this jacket

Great, year-round useable
Great for skiing, with a couple warm layers under. Equally great for a hot rainy summer day. Packs into very little space, weighs nothing, yet gives up nothing in functionality. Very comfortable, hood and neck really well designed for comfort and weather resistance. I'm on my second one - excellent jacket.

The best jacket out there!
I own stuff from Marmot and other top brands. I was skeptical about Arcteryx, but this thing is incredible. I wore it the other weekend in Rocky Mountain National Park and the wind was blowing 50-60mph and I was nice and warm in this thing. It is half the weight of another shell I wore the weekend before on the Dunes, and even though the wind was half as strong that weekend and I had an additional layer on, I was cold. I am not going anywhere without this jacket again!