Updated my Nexus 4
Battery seems to last longer. Having said that, straight after the update it wasn't possible to use the Contacts, Text and Phone app. Whattsap, which apparently is linked to the Phone one would crash too. No mobile connectivity possible, but WiFi was still working.
A few *basic* things that they didn't bother testing on a nexus 4... Odd!
Factory restore to wipe out all the data, and it's been ok since then.
Hadn't I been a techie I would have just given up, but I'm stubborn and persisted...