“Starting with Release XYZ there is no longer support for 32-bit code, so update your old 32-bit apps to 64-bit versions before you upgrade your OS to this release”...they mean it. Every major OS has done it, Windows, MacOS, Linux. It’s not rocket science — modern computers now need more than 4GB of RAM and 32-bit OSes are limited (modulo arcane tweaks).
The warnings have been coming out for many years. But do users listen to warnings? Some do, most don’t, so they get caught out, and that fuels the “Catalina is trouble” reports. And because there are more MacOS users than ever, the noise is louder.
But other than the 64/32 issue, Catalina hasn’t been significantly more or less trouble than any other MacOS release.
Catalina's problems went way beyond 64/32 bit issues. And putting aside 32 bit issues cavalierly are not helpful for those people who rely on 32 bit apps that don't have 64 bit counterparts. A short list:
Stuck updates
Disappearing reminders
Screen share problems
Server connection problems
Express VPN problems
Ringtone sync problems
Mac error code 1008F
iPhone sync problems
App update errors (some 32 bit, but not all)
Bluetooth connectivity problems
Keyboard connectivity problems
iPhoto not working
Wifi issues
iTunes remote app not working
Battery drain problems
AirPod connectivity problems
Excess CPU usage problems
AirDrop recipients disappearing
Apple ID setting problems
iCloud connectivity problems
Music library freezing
Safari extensions not working
Time Machine drive storage location changes and usage
HDR bug with external displays
Freezing/Crashing issues
Kernel panic issues
Security issues
HDMI issues
There are a lot more. Some can be fixed, others can't, but with a list this long, who wants to spend so much time troubleshooting?
I'm on Mojave. I'll be waiting for the next OS before bumping. Catalina is Apple's Windows ME