Big performance upgrade from 5.0. Very happy with it.
Those with the Nexus 5 that want to update to 5.1 either manually or OTA and live in North America, I suggest only using build LMY47D. There is a new build out (LMY47I), that is a minor bug fix for those in Europe.
And yes, 5.1 is a significant update over 5.0.2 in terms of responsiveness, speed of the UI and plugging the memory leak (at least for most people it does).