I'm a vim user since a couple of years,
I've got a pretty long .vimrc file,
and I was pretty happy with it. Until I read the source code,
composed of half a million lines of code; it's awful.
Feel free to try
vim --version to have an amazing except.
Mine supports farsi, tcl, can act as a netbeans server, can be integrated within Sun Visual Workshop, has some perl, lua, ruby and python bindings, iconv, printers, has some hand-crafted cryptography, diff, emacs tags, zip/tar/bzip2/gzip browser, HTTP/FTP/SSH, ex (A line editor written 30 years ago.) mode, a shitload of obsolete terminals, GUI and operating systems, ...
So I was waiting for the first release of neovim, until I stumbled upon vis. Martanne from the suckless (♥) community wanted to write a text-editor for fun, and it's now a complete clone of vim, in 20.000 lines of code, 25 times less than the original. Of course, there are some missing features (folding, ex mode, right-to-left text, GUI, ...), but I don't use them, so I don't care. The code is well commented, it's quite easy to fix bugs and to add features. The only thing I'm missing from my vimrc is the vim signature plugin, but it's not really super-essential.
So, if you're a vim user, and tired of its sloppiness and code quality, you should definitively give it a try (and contribute to) vis!