I am absolutely in love with this jacket! It's extremely light weight, and the fabric is very soft, airy, and cool. I have not yet had a chance to test it out in rain, but I have worn it out while snowing, and it kept me dry. I've also worn it on runs with temps in the high teens and 20s with very gusty winds, and this jacket, combined with a long sleeve tech shirt (or 2), kept me plenty warm! I can definitely see being able to use this jacket year-round. It has plenty of pockets, and it's extremely fast to convert into a vest. The sleeves can be easily stored in the back pocket of the jacket. In fact, the jacket is so light that you could even roll it up and store it in a pocket in a hydration vest or Camelbak which would be especially useful for long runs in the spring or summer when you want to carry it just in case you need it.
I really like the cut/fit of the jacket too. It's not poofy at all and is extremely cute. Of course, the fit would depend on if you got a larger size to be able to wear more layers underneath. I plan to wear at most, 2 layers under it so I got it in the smallest size I could wear so it wouldn't shift or move around much. I have worn it on runs from 3-23 miles.
I'm 5' 2.5" tall and 112 lb, and I got the extra small. At first I thought the sleeves were a pinch tight in the arm pits, but this loosened up completely after I wore it one time and haven't noticed it since. I do think that if I had ordered a small that the sleeves would have been long; however, they are the perfect length with the extra small. In my opinion, so far this jacket was worth every penny and would definitely recommend it to others for running or cycling.