well in my opinion a cell phone in any light contains sensitive information. I keep my old phone locked just in case it was stolen or lost. My iPhone is always locked. I don't have anything too hide from anyone but its my phone and has info that I may just want to keep private. From personal numbers and now emails and other info.
People lock your phone. You will thank yourself later.
when an iPhone has so much personal information like phone numbers, emails, texts, and most importantly, other peoples addresses then it should always stay locked and should rarely be seen by anyone other than the owner.
I had it locked in the begggining but took it off, its too much of a hassle, cause everytime i put it in my pocket I click the sleep button and putting the code gets annoying plus people near you can pretty much see it when u type it in. So far no lockey for me anymore. I don't let anyone handle my iPhone without me being there and I never take my sight of it, good thing is somewut big I can always feel it in my pocket