My husband and I dabbled in it a few years ago. It is popular among con-langers (people who create their own language, a harmless if somewhat eccentric hobby, J.R.R. Tolkein is a famous con-langer, technically speaking so was Zamenhof, the creator of Esperanto). Although we only dabbled in it for a couple years, we could hold entire (stilted) conversations, and read (slowly) stories and articles. I was more fluent in Esperanto than I had been in Spanish after 4 years of high school Spanish. It is so easy to learn that with slightly more application we could easily have been more fluent.

It was fun, and something I'd do again if he were still interested. I guess on my own I don't have any motivation to bother. I do wish more organizations would pick it up, because it would solve a lot of problems since it is so easy to learn and culturally neutral (mostly). Engineers, air traffic control... There's even an esperanto scientific journal, that I would like to publish in some day.