I've got a short 4 digit pin, just to ensure there's no pocket dialing. A few weeks ago I was out with friends and everytime I pulled my phone out it was either in some app, contact or website, got fed up and set a pin.
I've also got quite a bit of sensetive data, from codes to pics, so probably better that I lock it.
Samsung GALAXY S4 32GB Exynos Octa Black Mist
Samsung GALAXY S2 16GB Exynos Dual Ceramic White
Apple iPad 4 16GB White WiFi+LTE
"World can't hold me, too much ambition"-Jigga