Interesting. I don't think I've heard of it before.

I learnt Esperanto grammar in about 2 weeks about 25 years ago. As my first second language, it helped me to understand English (my native language's) grammar better, and was later a useful bridge to other european languages. While I've forgotten most of my Esperanto vocabulary, I still have a good grasp on the grammar and how to form all the different conjugations.

I think that Interlingua sounds nicer, even though it's a bit more complicated. I never learnt it properly, though.