If you are happy with 16.3, don't upgrade. Sure, there will be some improvements as mentioned above, but don't upgrade because of FOMO. Zorin OS 16.3 is still supported until April of next year. Unless you have a good reason to upgrade I would honestly advice to wait if you are happy with what you have right now. That is also what I'm doing myself.
You can always run a virtual machine and install Zorin OS 17 there, to see if how you like it: