I went about six months without cell service a few years ago. The only deal breaker is this one - that lots of services require SMS authentication and won't accept Google Voice/similar. GPS navigation is a bit worse, because you have to pre-download the maps and don't get realtime traffic. You also can't be contacted when you're away from wifi; this wasn't a problem for me but I can imagine if you had kids or something it would probably be another deal breaker.