Don't Install If You Use Specialized Software or Hardware
Do you rely on special apps or hardware on your Mac? If so, hold off on the upgrade as many of these devices aren't ready to work with the new security features, and may not see an update soon.
Logic Pro X users that rely on instruments and adapters should hold off. Native Instruments says not to install Catalina as they look into how to deliver compatibility.
With the iTunes change, macOS Catalina isn't great for DJ's. Apple says, "The Music app on the Mac is brand new with a modern library format. The frameworks for access to the library are still supported for developers to directly access music on your Mac, however, XML file support is no longer available on macOS Catalina. Apple is working closely with app developers to make sure their software is updated and compatible with Catalina. However, customers that are using an app that is not supported should contact the developer directly, or if it’s a mission-critical app in their workflow, we recommend they continue using that app on macOS Mojave until the developer updates. iTunes on Windows has not changed, so apps should function as normal."
If you use anything resembling these types of tools on your Mac, check with the developer before you upgrade.