If Ribbons are implemented well, they're great. But often they're not, and then they're terrible. It takes a lot of work to properly organise a Ribbon for a complex program. Microsoft nailed it for Office, but programs like AutoCAD are still not well done.

Microsoft have put together an awesome guide to the Ribbon. Even if you're not making one, it's a great read that really goes into the reasons it exists: https://docs.microsoft.com/en-us/windows/win32/uxguide/cmd-r.... I came across this page by chance when I was in high school, and I think it was what sparked my interest in user interface and user experience design.