I insisted on having some kind of case on my N4 before I would take it out of the house. I admit, the glass back has made me very nervous. I initially bought a "official" replica by Shenit for £12.95...
I have not seen a genuine official bumper case in person, but this copy does seem to look just like it. It retains a very stylish look, and the buttons are fantastic. However, I still found myself feeling very nervous handling the phone day to day. The black plastic part of the bumper only protruded back and front by a tiny amount, and I felt that this wasn't enough to protect the phone when I place it down or if I were to drop it. Also, the black plastic part wasn't soft enough for me. I would have preferred if it were made of a softer silicone material, as this may have given me more confidence that it would provide some drop protection. As it was, I felt that the only protection offered by this would be that it would prevent the edges of the phone from getting scratched.
Obviously I do not know how this compares to the official bumper or the GENx one above. Do those protrude enough to protect the screen and back? Is it made of a softer material that might absorb some of the shock from dropping the phone?
Since buying that bumper, another case came along that seemed like it would offer much better drop protection for the phone...
I have bought this (@ £13.70 including shipping) and whilst it isn't the best looking case in the world, it certainly does look better in the flesh, I have much more peace of mind that the phone will be better protected and I find it actually feels good in the hand too. It doesn't feel half as bulky as it looks like it would. For now, this is what I am sticking to and the bumper is staying on the shelf.
Whilst I really do like the design of the phone and it is indeed a shame to cover it up, the design certainly wasn't the factor that made me buy the Nexus 4. As such I don't feel I am doing it a great injustice by covering it. I am simply protecting my investment.