No cellular network after OTA to lollipop (Nexus 4)
UPDATE2: After a while, it seems like it cured itself. No more connectivity issues for a full 24 hrs. Perhaps it was a bad tower-radio(baseband) combination?

UPDATE: Actually, this didn't fix it completely. It behaves better, but it eventually goes into a state where the antenna says 3G, but there's no data nor phone connectivity. This happened 3 times.

So, I think I fixed it by updating the APN address to epc.tmobile.com, switching to 2G only and rebooting, switching to 3G and rebooting.