I mentioned what's easy about Esperanto... now here's a rundown of its problems.

The main issue is that Esperanto is underdesigned.  The original [pamphlet? textbook?] promoting it contained only 16 grammar rules and 925 roots.  These were simply not enough for a complete language, and so the initial followers, mostly Europeans, filled in the blanks, solidifying the grammar rules and adding new root words, leading to inconsistency and Euro-centrism in certain respects.  

For English speakers, luckily, the meaning very often matches English.  For example, crono means "a crown" and croni means "to crown", which means the same in English as in Esperanto: to corronate.

An extra problem comes when forming adjectives, compound words, or adding affixes; it is not always clear immediately whether a morpheme is intended to have its noun meaning or its verb meaning. Does "konata" mean "known" (participle of the verb koni) or "an acquaintance" (from the noun konato, a person who is known)?

Because of this confusion, it seems to me that Esperanto speakers tend to be careless in their word formation, making Esperanto substantially more difficult to read than to write.  It's not so much that you can't figure out what something means, just that you have to think about it for a minute, and interpret words according to context.

An older thing I wrote a while ago...
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