I have tried to learn Esperanto. Its grammar is as easy as people claim it to be. The most difficult parts, as with any language, are learning vocabulary and finding somebody to practice (unfortunately hard for what strives to be an international language).
Still, at least to me, it feels more like a strange mixture of various european languages than its own thing. One could say it makes it easier to learn, but for me it shows that Esperanto cannot be considered truly international, as to people who are neither from Europe nor from an English-speaking country (who might even be using a diffrernt writing system) it still feels as foreign as English (albeit easier to learn).
I still like the ideals that inspired Esperanto and find conlangs to be a lot of fun. Still, if any language is going to dethrone English in coming years, existing languages like Chinese and Russian have more chances to do so. Meanwhile conlangs like Esperanto, Lojban, Interlingua and Toki Pona are still a very great way to meet like-minded people.