I just updated the firmware in my Nikon 5100. And I did it all by myself. So what was the update all about. Answer is: Nothing and everything.
I say nothing and everything because the manufacture will give you reasons for the update and you may read them and decide you haven't got any reason to update the firmware in your camera and you'll pass on the firmware upgrade.
Don't. I'm telling you to do the firmware update no matter what you think. The reason is simple. Manufactures lie. They all lie. Every single one of them.
Their lies are lies of omission. It's what they NEVER tell you that is the big reason for doing the update of the firmware in your camera.
I know they lie because I worked in the computer industry for 30 years and I was one of those nice people that would announce the firmware updates. I REALLY knew what the update was for because I would force the engineers to tell me. If they didn't I wouldn't release the firmware to our customers.
Camera manufactures are no different. No manufacture will ever tell you what really goes on. It's in their DNA.
So when your camera manufacture releases a firmware update get it and update your firmware.