I carried my phone around naked for a while, savouring the small profile, but got increasingly worried about breaking it or getting it covered in paint or something. I broke my previous phone by carrying a flight case in such a way that it pressed on the screen so I wanted a cover that protected the screen.
It adds a little bit of annoyance that you have to flip the cover back to use the phone but it adds a lot of confidence.
And I discovered a bonus I didn't expect when I found that the cover flips over to become a stand. I use this feature most nights as I use Alarm Clock while the phone is charging and it holds it at exactly the right angle. Good for watching videos too or keeping the phone upright on a desk.
All the controls, sockets and cameras have good access, although the flap does make it more awkward when you want to use the back camera. On the plus side though, as a cameraman, I discovered that if you flip the cover open onto the back of the phone, then slide it round another 90 degrees so its lying along the edge of the phone, you can use it as an adjustable sunscreen (french flag) to keep flare off the lens and screen! At the same time I got this, I also got a SliqShield to protect the front. It makes it a bit of a tight sequeeze but adds "in use" protection to "in pocket" protection. Please buy this so they keep making them and I can get one for the iphone5 when its time to upgrade!