I have had it on my 2013 Nexus 7 for a while now and while there are some great new features and layouts I have had many slow down and unresponsive app problems (mostly in Chrome) My Nexus 5 had the same problem until I cleared the android cache partition but it didn't work for my Nexus 7. 

It's a step forward and very easy to pick up but I am struggling to see where they are going with Android. I have a Nokia 920 for my work phone and an currently warming greatly to windows phone 8.1. I miss the widgets but its much more responsive and actually works well in a MS Office and online environment. Cortana is great as well I find I am using it more and more instead of pressing buttons.
 

I started having problems with Chrome running really slow, general unresponsiveness of Android, and lock ups, so I'm trying the clear cache method suggested here: http://www.gottabemobile.com/2014/12/15/moto-360-android-5-0-1-update-rolling-out-today/

Yup, it definitely helped.