As much respect as I have for Sonja Kisa, I have to say that one particular feature of Toki Pona has violated my expectations of a language so much that I have managed to devise a language law or aphorism for it: that any language which requires more than five words to say the noun "duck" is clearly quite dazzlingly broken.
Rather like Old English, Toki Pona is limited in its range of nouns—in fact, there are only 118 words overall—which means that you have to use a phrasal circumlocution to denote most objects. For example, a housemate is jan pi tomo sama, i.e. person-of-habitation-same. I can see how such a word doesn't deserve a radical, and I can fathom the rationale and the free philosophy behind a language based on the odd juxtaposition of Taoism and the Sapir-Whorf Hypothesis (there's a-whole-nother essay), but what I cannot in the least bit comprehend or find in the least defensible is that startling omission from the core vocabulary of so primitive and ubiquitous a thing as the common duck.
It took me a while to find out how Toki Pona speakers talk about ducks. It was first suggested that telo waso (water-bird) be used, but how poor is a language that cannot distingush 'twixt duck and swan. Soon enough however, thanks to Google, I was led to a Toki Pona translation of Monty Python and the Holy Grail, which includes the following:
ARTHUR: A duck.jan Asa: waso li awen lon sewi telo.
Therefore... Toki Pona is witchcraft! Er, wait, no. Therefore, duck in this translator's bemuddlefraught mind is waso li awen lon sewi telo—literally bird-that-resides-in-above-water, or, as Cody put it, "bird that stays on the water". Which still doesn't differentiate it from a swan, and moreover doesn't provide any more information than telo waso. I must say that the language's free-flowing fun philosophy comes over more as a desperate grasping for War and Peace sized phrases to describe what should be endearingly simple concepts. This simple language, by an overly forced simplicity, is anything but.
On the other hand, it isn't all doom and gloom: for example, there are two separate forms for saying "goodbye"; one for the person that is leaving, and one for the person that's staying behind. This seems to be a problem more poignant for users of realtime chat than anyone else, since often one person's leaving will inspire others to do the same, prompting no one to know who's still around and who isn't. It's a bit like how some eastern languages structuring numbers as "two-ten-one" for 21 allow children to learn to manipulate numbers more easily since they're already divided up into neat little sections. Seventeen minus nine is a calculator job, whereas one-ten-seven minus nine can be done by taking the nine from the ten and adding to the seven: eight. But just try adding ducks up in Toki Pona!