Jason B.wrote a review of Patagonia Bivy Down Jacket - Men's on January 6, 2017
Familiarity: I've used it once or twice and have initial impressions
Fit: True to size
I've been looking for a jacket that's good for day hikes and general use up here in the damp and chilly Pacific Northwest.
Medium is perfect for my height and swimmer's build. I can easily put a Medium Patagonia fleece underneath it, and or a Medium Patagonia Torrentshell rain slick over the top for heavy rains, although the Bivy Jacket alone sheds drizzle just fine.
Very happy with this jacket -- it will replace my The North Face Apex soft shell without hesitation. I used to have a Medium Patagonia Down Sweater (full zip), and surprisingly those are only $20 less than this Bivy Jacket at full retail price. Arguably the Down Sweaters are better for serious athletic feats due to their packability, but for that extra Andrew Jackson I'd say you get more than your money's worth with a bit thicker puff and a very durable woven nylon outside on the Bivy Jacket. If you're in the market for the Down Sweater, think twice because the Bivy Jacket might be a better choice depending on your activities.
Lastly, the left-handed zipper on the Bivy Jacket is cool, I enjoy a little ambidextrous challenge.