I updated earlier today. I will be the first to admit that the updates to the OS it self are few and far between. iOS 5.1 is really just a series of bug fixes more than anything else. That being said, I did notice SLIGHTLY better battery life than I had with iOS 5.0.1. The camera button always being on the home screen is a nice edition, although I was hesitant until I noticed that they fixed a bug with it. No idea if anyone else ever experienced this, but in Windows, if you tried to rotate a photo that was taken with the iPhone camera, but you accessed the camera from the lock screen, you couldn't rotate the photo. It seems to me that that glitch has been fixed.
My final thoughts on iOS 5.1? I like it, although I do still have a list of things a mile long that I would like to see added in. I think the update is worth it, though.