When I first learned about Esperanto as a teenager, I was excited and intrigued. The concept of a universal language that was easy to learn and that could connect people from all over the world appealed to my sense of idealism and global community. But this was long before the birth of the World Wide Web, and it was difficult to find resources for learning a language that was spoken by so few people. I abandoned the idea fairly quickly and focused my attention on other things instead.
Now that the Internet has made it possible for Esperanto speakers and writers to find each other easily, I'm sure it would take me a very short time to become proficient in the language. The grammar is purposefully simple, of course, and the vocabulary is quite familiar to anyone who has Spanish, German, Latin, and English under her belt. But I've decided that my time and energy are better spent on the many natural languages that exist. Esperanto, for all its lofty goals, no longer appeals to me as a feasible solution for worldwide communication.
My biggest objection to Esperanto is that two of its major ambitions are directly at odds with each other. Esperanto advocates want widespread adoption of the language, while still maintaining the strict rules of grammar which keep it consistent and easy to learn. I believe there is no way that a language, however planned or artificial, can remain static if its usage is extended. We see this with computer languages; even with the publication of standards and the existence of compilers and interpreters which force adherence to the rules of syntax, users are constantly attempting to tweak the languages for efficiency and elegance. Esperanto will suffer the same fate if it is widely adopted.
My other problems with Esperanto are in the language itself. As I've illustrated in previous posts, the characteristics of natural languages that make them difficult to learn are precisely those which give color and life to those languages. The exasperating subjunctive in Spanish, the convoluted word order and page-long sentences in German, the multitude of indefinite articles in Chinese---all of these idiosyncrasies are manifestations of the richness of the history and culture of the speakers of those languages. Esperanto, despite being criticized for being too European, by design has none of these delightful features. Language heavily influences thought, and the flatness of Esperanto is reminiscent of the Newspeak of George Orwell's 1984. Doubleplusungood, indeed.
I could be wrong about all of this. In fact, I'd kind of like to be wrong, because anything that helps to build bridges between people of different races and cultures is a good thing in my book. I just don't think Esperanto is that solution. For now, I'll leave it to others to blaze that trail.