Just to offer a counter viewpoint for balance - I am an upgrade whore
Admittedly a lot of that is as a plugin developer I am usually wanting to take advantage of some change in the codebase to be able to offer a new feature.
But even if I wasn't developing plugins, I would still upgrade regularly. You might not see something immediately obvious in the change list (or even understand much of it) but there are continual bug-fixes, performance or usability improvements that often will become part of your everyday workflow once you become aware of them. They can be for the most subtle and intermittent of issues - like a problem with the cover browser causing Calibre to crash sometimes which a recent fix seems to have sorted.
Or a feature like downloading metadata/covers which you may find not working with older versions the next time you go to use it without the latest version workarounds...
Lady Fitzgerald's advice of waiting a few days is perfectly sensible if you are concerned you will hit a buggy release. There was a rather bad month a little while ago. However that is the exception rather than the norm - besides someone has to use it to find and report the bugs!
Having said all that - if you are perfectly happy, you don't experience any crashes or bugs that irritate you, are perfectly happy with the functionality you have and have no desire for anything else such as what the various plugins can offer... then stay where you are for a while longer
