I switched to vim a year ago, and I fucking love it. The one thing I miss from ST2 is column editing/multiple cursors. Column editing fulfills the same kind of need as basic usage of vim macros, I think (i.e., applying some kind of sequence of edits to multiple rows), but it's visual and you get instant feedback (across all rows), which makes it easier and something you can sort of feel out iteratively.

For example, supposed I have a row like (making up these names as I go, and suppose the list is longer):

  Controller_Section
  House_Model
  Person_To_Category_Selector

and I want to insert after the first underscore the word class, so I'd get Controller_Class_Section and so on (this is a contrived example, but one has to do these kinds of things sometimes.)

In vim, I think I'd record a macro, but I'd probably forget some parts (like moving to the next line at the end) and have to undo and whatnot (could use a regex too, but that's a bit harder--I'm practicing recently to be able to do it more effortlessly.)

In ST2, what you do first is create a cursor at the beginning of each row (option + down arrow on OS X.) Then you move ahead one word (Opt + Right arrow on OS X.) Now the cursor is right before the underscore, even though the underscore is in a different position on each row. You can see that it's in the right place on each row, so it's hard to make a mistake, and if you need to do something more complicated, that remains true. Then, you just type _Class, and it types live on each row, once again making it so you get instant feedback, and it's hard to make a mistake.

That to me is the biggest actual advantage of ST2 over VIM, but there are other reason to not switch, like vim's steeper learning curve (when most of us are already busy, and learning other stuff at the same time), and the fact that some people prefer the mouse, which behaves strangely in vim.