On my 640, best build so far.
For the past three previous builds, the phone was increasingly slow. Phone app took roughly 15 seconds to open, Photos app 10 seconds, Whatsapp 7 seconds and so on.
I did a hard reset before updating to .164 (and got a working Lumia Camera back as a nice surprise), and now they open almost instantly.
I also noticed that the Storage Sense usage details refreshes way faster than before, both on internal memory and SD card.
Alarm was always ok to me.
On the previous build, my pc couldn't detect my phone anymore, but I have yet to try it on this one.
Overall performance is really good, so if you are suffering from the same problems, it's a nice idea to give it a try, but I restored my backup in the process, instead of the recommended fresh start.
It's also worth pointing out that hard reseting freed a nice amount of system memory usage (in Storage Sense), reducing it to 4.4GB (was around 4.8 before). To my surprise, after updating to .164 and updating all the apps, the amount was further reduced to 3.8GB. A very welcomed free space.
And I don't know about you, but sometimes, when I'm downloading a build and it fails, when I try it again, the required space goes drastically higher than it was originally (in the previous build download, from around 850MB to 1.23GB), and this was the culprit that motivated me to hard reset, since I had nothing else to remove to free actually more than the required space, and the system apps do a poor job in internal memory consumption.