This is far and away the most disruptive major update to macOS in recent memory. My experience of the past few major versions have been almost entirely seamless.
I see! Maybe because I wasn’t running any 32-bit applications, it was rather seamless for me.
I haven’t had a bad experience with Catalina, but the new app sandboxing has broken a few minor tools like BalenaEtcher. Not a big deal as it still runs fine under sudo... and they’ll surely release a new version shortly.