Unfortunately, that's something you won't know for certain until you try.
Obviously, make backups of all your current work BEFORE you open and save in a newer version. That way, you can always go back to the previous version.
Breaking changes are shown HERE for the latest stable release.
If you upgrade then find that something no longer works as previously, then it could be down to a breaking change, and I'd suggest posting in the How Do I section with any issues.
I will say that not upgrading would be foolish, as many bugs have been fixed, and new and improved Plugins/Behaviors introduced.