AT&T Note 4 Lollipop...

Seconded. I have a Nexus 7 2012 WiFi that I use to "field test" new Android releases. I haven't taken the time to load 5.1 on it yet, but I did load 5.0, 5.0.1, and 5.0.2, and while it got better in each release Lollipop has changed the N7 from "what I use in the evening" to "what I recharge every couple of days because ain't nothing I want to do worth that amount of waiting on everything", and I factory reset it between each release.

Granted, the N7 is much older and slower hardware, but it was pretty smooth on KitKat.

Looking forward to seeing what 5.1 does to it. Maybe this is "Lollipop done right", maybe it ain't, but between all the Material brightness that I don't really favor and the newly-introduced lag to my trusty old N7, I'm really not jumping on the Lollipop bandwagon on the first day if I can help it on my Note 4.
 
I think by the time its ready the Note 5 will be around the corner for my annual upgrade come October. But only if it comes with a removable battery and SD card support, unlike the S6.