There are two important considerations.
Unless there is a feature of Catalina you are eager for – WAIT.
I highly recommend keeping Apple devices updated (and upgraded). It’s part of what we are paying for in that “walled garden.” Apple is taking personal privacy and data ownership seriously. They don’t have the same Market Forces with regard to collecting or protecting your data. Updates are typically Security Patches. Catalina is more than an Update. It’s an upgrade, in my opinion. So I say WAIT!
But there are other major considerations. #1 is that Catalina will not run 32 bit Apps. If you’ve been an Adobe customer for any length of time, there’s a good chance you have many Adobe associated 32 bit Apps. The Installer does let you know which Apps will not run, so you can back out at that time and check with the developers for a compatibility update. Be prepared for some developers to take the opportunity to upgrade their products and charge for the same.
You can use the System Information App to find the 32 bit Apps you might be using.
Here’s a good article with their reasons you might want to delay upgrading to Catalina. You will upgrade eventually, and it won’t be long until the 10.15.1 update is released. That’s usually a good time to jump for most people. I’m upgrading after posting this. I figure it’s part of my job to walk the cutting edge.
Catalina has been released and Apple wants to you install. There are good reasons to do so. It doesn’t have to be right away. New computer owners won’t have a choice. But everyone else should WAIT until the next release