Amazed by Kitkat/ART performance and battery life
I have a GSM Galaxy Nexus, a phone which many of you know has questionable performance and battery life running Jelly Bean. After switching to a KitKat ROM and enabling ART, my phone is smooth enough for me to not have any complaints and even better, it has greatly improved battery life.
My usage consisted of reddit apps, rss apps, messaging, and light gaming. Screen brightness followed Velis Auto Brightness's AMOLED dim curve, which was dim in very bright rooms but still clearly legible.
Performance improvements: the phone no longer feels like it is running out of RAM (in settings>apps the RAM usage due to always-running services is much lower). I can have many apps open at the same time and switch between them with little to no waiting for the phone to respond to my input. Especially on ART, touch response seems to be much improved and it feels like the on-screen elements follow my fingers much more smoothly.