They are utter garbage; there isn't a single good Catalyst app, they're all putrefactive shit on the Mac. The JIRA app — which Apple demo'd on stage when they unveiled Catalyst — is hands-down the worst app I have ever used on the Mac, and I've been using the Mac since I was like 13 and my mom had an SE30, and I also spent 2000-2008 as a developer of Mac apps (iGet, iGet Mobile, and worked on some others).
SwiftUI is still kind of painful, but way less painful then it was at launch. SwiftUI is an interesting new paradigm, and it really does seem that it will be good someday, and even possibly soon. It's already awesome if you happen to not hit the (many) areas where it is still lacking.
Catalyst will never be good, and Apple will kill it as soon as they possibly can.