I never had an issue figuring out the front or back. Usually my fingers run over the home button or the ear piece which is what tells me what the front is. Honestly, I didn't even feel the edge till I repeatedly turned the phone around quite a few times, which is when I looked at it. Not sure this would let me determine what the front was, but that might be my personal opinion, or my insensitive fingers.
I think the iPhone 4/4S is a revoltingly bad industrial design, and am utterly flummoxed by the acclaim it's received. The iPhone 5 looks pretty good but I haven't actually held one yet.