Of course it's an improvement. You know what I used to do when new versions of my browser came out? Update manually. Now to get the same result I do nothing. You know what my parents used to when new versions of the browser came out? Nothing. Which after a few years can be a problem.
If you don't want the computer saving you work then (1) IMHO you're not really getting the point of having one, (2) you can configure Firefox to not update silently.
If you don't want the computer saving you work then (1) IMHO you're not really getting the point of having one, (2) you can configure Firefox to not update silently.