Thanks for linking to the article. For me, what's refreshing about Lotus Agenda is the ability to create views of your own data, something you don't see today unless you are using enterprise cloud services.
As Bob Newell (linked in the article) notes, Emacs and Org seem to carry this torch today. There may still be a few tricks unique to Lotus Agenda and such tools, but Org mostly surpasses them, and its flexibility and extensibility go far beyond what Lotus Agenda and its primitive macro language could do.