Theoretically, I’m pentalingual. I live in a city where most people are trilingual anyway. Almost everyone in Ahmedabad understands English, Gujarati and Hindi, albeit their levels vary widely.
All I did, was walk two extra miles and learn Spanish and Esperanto.
I’ve been doing Spanish for nearly five years now (though with long gaps in between), but I would still think twice before grading myself intermediate. I’m still weak at past and subjunctive tenses.
Esperanto, however, is a totally different playground. I’ve been learning it for hardly 20 days, but I have a feeling that within an equal amount of time from now, I might pretty well be intermediate.
The secret lies in the beauty of the language. Since it is a conlang, it has been well thought out, with the prime purpose of making life easier for learners.
Everything works according to a set of 16 simple rules, and the vocabulary is meagre, thanks to the Lego approach it follows. Yes, you can build your own words using the base forms and affixes, and rest assured that your readers will understand it — which makes the language far easier to learn and understand.
Take the example of the English words good, better, best, bad, worse, worst, well (as in well done) and badly. Add to it the forms of great and awful.
All these words, although related, have hardly anything in common when it comes to the way they are spelt. Come to think of it, for a newbie, good and better do not sound like they are brothers. They just have to be remembered.
On the flip side, in Esperanto, all these words can be constructed from the same base: bon. Just by adding all sorts of prefixes and suffixes, you can form all the words mentioned above, simply using the base bon:
bona, pli bona, plej bona,
malbona, pli malbona, plej malbona,
Great and awful become bonega and malbonega.
Isn’t it just great? With Esperanto, you soon start feeling as if this is how a language should be.
But apart from simplicity, the great thing about Esperanto is that it has a community. Rather than just a language, it is a movement. You might want to read its interesting history at its Wikipedia page.
And if you feel interested, do not hesitate, start learning it. You’ll sure find some use of it some day. Learning is never a bad thing.