In a nutshell, I would suggest this jacket as an outer layer in the fall (above 40°F) in domestic climates or as a mid layer in colder climates. I would not recommend this jacket for hiking. I was very intrigued by the Thindown fabric in this jacket, especially given the same warmth rating as E.B.'s Stormdown 800 fill jacket, but I don't feel it compares quite the same. When worn as an outer layer in 20°F weather with low wind, this jacket always had cold spots for me, mainly in the shoulders and forearms. Also, because of the more sheet-like nature of the jacket (as opposed to a rib-like structure of a classical puffy jacket), I often felt air moving out of the jacket's waist or neck when walking normally. I don't think this contributed to considerable heat loss, but heat loss nonetheless. After trying a size smaller (M instead of a L) to try to get rid of these issues, I found the fit was much better and there was less air escaping, but the cold spots remained. I purchased the Stormdown to compare and found it considerably warmer. With the Evertherm, I never really felt warm, only protected or on the brink of chilly. With the Stormdown, I felt cozy and confident. In fact, I had to wear both the M and L size Evertherm jackets together to feel comparable to the Stormdown, and even then my shoulders still had cold spots. Perhaps if the incredibly thin (and impressive) sheet of Thindown in the Evertherm was just a bit thicker it would perform incredibly well. This was the case in the armpits where the fabric was essentially doubled - super warm! This inconsistency in warmth, however, along with no packing pocket makes this jacket a no-go for hiking. E.B. even suggested to me in an email not to pack it tightly lest I risk damaging the Thindown fabric. In all honesty, however, I was only moderately-to-mildly active in this jacket and never exerted myself, which may play a key factor in its warming abilities. Still a great 3-season jacket though, and stylish!