True story....I've had a Sprint 4S since launch and have never been able to upload an Instagram photo once while on 3G. It always times out because the connection is so horrible. This happens in 4-5 bar areas too.
4-5 bar areas? LOL. You do know that signal bars have nothing to do with data right? Thats for voice, not data...I have zero problems with Instagram or any app really with my 4s. You must be in an area that doesn't get great data service, sucks.