Our policy at USV is that all of our devices need to have lock screens. So I have one on all my phones, tablets, laptops, and desktops. I don't mind it very much. Except when I want to take a quick picture or video of something that is happening in real-time. In that situation, seconds can make the difference.
The folks I know who use iPhones can put their camera in front of the lock screen. I am not sure how they do that, but I know they do. For the life of me, I cannot figure out how to do this on Android.
This is a cool feature. I'd like to call it out as something every mobile OS should have. If anyone knows how to make an Android device do this, please leave it in the comments. If it is not possible, then this post is a feature request to the Android team to make it happen in the next build.