Sure thing. It's probably easiest to explain by comparing it with the other options. You could say that Vim is one end of a scale (Hardcore keyboard power usage), and Coda/Espresso are on the other (Very designed, and try to do pretty much everything). I really like Chocolat because it's a sweet spot in the middle for me.
I get a beautifully clean experience like in Vim, along with plenty of useful keyboard shortcuts, but still a pleasant UI, regular cursor, and convenience features like a file browser, highlighting recurrences of a word, quick jump into my recent projects etc.
It's not that it does one particular thing that other editors don't (Feature-wise, I can't think of anything that only Chocolat does). Instead, it's the combination of what it does and doesn't do that I like.
Vico sounds good, but in the demo screenshots at least, there's just too much going on for me. Not major differences, but Chocolat seems to get by great without the toolbars along the top, and each screenshot for Vico has too much happening (Split editing, symbol browser etc.).
It may be possible to tweak Vico to work in exactly such a way, but even the choice of screenshots, yellow background etc. shows the developer's personal taste. I want the editor to be as minimal as possible, without being quite as extreme as Vim. It's nice to find an editor which seems to have the same goal, and then sit back and let that developer work out the best way of achieving it.
Also, there hasn't been a tweet from Vico since March sadly. The active development speed does make it a bit more fun to be using Chocolat. Even if they aren't big updates, it's just nice to know things are happening :)
Well yeah, you're right on every account. But Vico is moving in the general Chocolat direction (I'm active on the pathetic help site since before AppStore release), while being scriptable in Nu (a kind of objc+lisp) and having a working VIM mode (as it is it's only mode).
It doesn't have the visual polish yet, though. Or proper dev-to-community communication habits.