I don't really understand the fuss. You can edit Clojure with any text editor, right? Syntax highlighting, auto-complete, auto-indent, etc are nice features to have, and I do use them, but not really necessary for learning a language. If the language is interesting, I will learn to edit it in vim regardless of whether it's well supported.

Then again, I am probably not a good sample, since I eschewed Eclipse for notepad back when I was learning Java before I discovered linux and vim. Regardless, I still hold the opinion that it is a good mental exercise to occasionally hack the raw text without all the bells and whistles of an advanced text editor/IDE in order to internalize the language structure.