This Nike product SAVED me. I had just moved and was in desperate need of a layer for chilly evenings and mornings (I'm a morning runner) and this was perfect! I used this as a layer directly on top of my sports bra, and the fabric was so comfortable and kept me at a comfortable temp for ~40-50 degree mornings. The little thumb holes are a great touch, and the sleeve length was perfect for me (sometimes they are a bit too long, which is a bit uncomfortable when you're running and moving your arms though I suppose I am lucky I don't usually have to worry about them being too short!). They also protected me on the fateful day I finally fell on one of my morning "easy" runs: my arms and hands were unscathed and the sleeves stayed intact!!
The midlayer is also great for adding a bit of warmth on cooler evenings when you don't want to go full sweatshirt but a nice extra layer is definitely necessary (I am in the bay area now and having layers at ALL TIMES is essential). The quality and feel of the fabric, both inside and out, makes it such a nice thing to have when you're out and need a jacket for warmth. the one thing I am a bit ambivalent about is the fact that there are no pockets. I think that this is ultimately a good thing (especially since there are thumb holes to keep your hands warm, and don't need pockets to do that), but something to note in case you care about having pockets. I think they tend to get in the way and add bulkiness when it is not necessary. I usually have a running belt which suits me much better.
Finally, the quarter-zip is, for me, the perfect length and I find useful to help mediate the level of warmth I need. Nothing like zipping all the way up to cover yourself when you're chilly, but sometimes when you're out on a run you need to unzip a little to cool down. The zipper is smooth, and also non-bulky which is a plus.