I upgraded my Sprint 8703e to 4.5, and it seemed to work ok, except as soon as I rebooted, it would just go into a reboot loop.
I wiped it a few times and 4.5 always installed, but then failed on a reboot.
I'm back on 4.2.119. Works rock solid, no reboot issues.
Too bad, I liked the new OS a lot, but oh well.
I guess I'll have to upgrade my phone someday.