This may sound a bit provocative but it actually is a real question. Feel free to edit if you don't like the tone.
Now, as much as I understand vi from my short experience with it like 10 years ago, it's a primitive text editor with one editable line at the bottom of the screen created before the scrollbars were invented, with some crazy shortcuts to overcome this limitation.
Can somebody explain me how one can be more productive with it than with, say normal VS.NET editor? Moreover, why would anybody want to use viEmu which supposedly turns your VS.NET into an ancient vi?
I'm willing to give it a try but I need some motivation to overcome the learning curve.
The viEmu page itself has a pretty good article that might help to answer your question: Why, oh WHY, do those #?@! nutheads use vi?
I've spent the last couple months trying to teach myself to use vim "properly" and now I can hardly stand using other editors because they seem underpowered and clunky. For a random example, imagine you have a line of code that looks like this:
$welcomeMessage = "Welcome to SiteName!"; // shows at the top of homepage
In a normal editor, how would you change the string? You'd probably have to reach over and grab your mouse and carefully select it, or you'd move your cursor inside the first quotation mark, and hold down Shift and the right-arrow until you got to the closing quotation mark.
In vim, with my cursor anywhere in-between the quotes, I type ci" and it erases everything inside the quotation marks and puts me into insert-mode so I can type the new value I want. My hands didn't even have to move from my normal typing position.
There are so many things like this, I think you really have to spend a while using the editor to understand how powerful it is. It's very slow and hard to use at first, that's why a lot of people try it for a short time and think "this is dumb, everything is way harder", but after a while you start thinking in terms of the motions, it all starts to become automatic and it's much, much faster than using a "normal" editor. As I said, I can't go back now.