Glad this is finally out for the Nexus4, was holding out for 5.1, and am just wiping and flashing from scratch. Been a couple of issues where the phone was just completely non-responsive, required power button to be held. Been using an iPhone 4S for the last week!
Hoping this will sort things out, and if not, I guess I'll try CM12 before looking for replacement.
Still quite impressed with how the 2012 Nexus7 is holding up, it's way past its prime, but still struggling on.