Saluton! First of all, I'd like to give my huge thanks to the Esperanto team for working so hard on this course! I've been waiting a long time and I'm very happy that it's finally here.
So far, I'm not having a difficult time with the tree. I've got the first section done, and I'm debating whether or not to practice what I've learned or continue with the tree. I'm loving being able to learn Esperanto with Duolingo; I find it more fun and easier to stick to than Lernu, but Lernu gets you understanding what's going on pretty quickly.
I own The Wonderful Wizard of Oz in Esperanto and I've been waiting to learn Esperanto so that I could read it! I plan to get through the tree before I start reading it, so that I'll have something to do once I finish the tree.
This isn't a very long post, but it's pretty segmented, so I apologize for that. I want to make a post with the various resources I've found for Esperanto in the past, so I'll probably get that up soon.
I've known about Esperanto for a long time, but I never really considered learning it until Duolingo released their Esperanto course. Now that I've studied a small amount, I'm so impressed by the language and its potential to facilitate language-learning that I think I'll make Esperanto one of the languages I someday want to be able to fluently speak and understand (along with French, and possibly Spanish... and Indonesian... or Mandarin Chinese... or Bengali... or...).