How do they compare to the DevXpress ones or the original MSOffice ones.
Are they worth investing time in them (for practical usage now, not academic curiosity which I'll do anyway)?
From my experience, the new ribbon control implements the entire specification as laid out by Microsoft. The only issue I noticed was a slight flicker when the form was resized which caused one of the sections to collapse or expand.
Worth spending time in? Definitely, as they are lighter weight and its a matter of time before someone gets rid of the flicker (could be as simple as a lockwindowupdate inserted in the source?). It doesn't hurt to use the Delphi action manager, from which all is based.