Sure, so much fixed that it hasn't accepted any change, not even changes by its own commission who recommended modifications to make it a better language. That better language was named Ido. But the Esperanto zealots rejected it. Read the Wikipedia page about it.

What I don't like in Esperanto, mainly:

• Its use of specially accented letters which are non standard (look at difficulties people have to post on /. in Esperanto!)
• Its over-use of negations. So much that many words only exist in their negatively-constructed form (good -> "bona", bad -> "mal-bona"). This is counter-intuitive, why would I think negatively for 50% of words?
• Not really used in any useful places

To summarize, Esperanto is a (successful, compared to Ido) fork of the main line which changed it name to Ido. [troll mode off]