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.
EDIT: Thanks to everybody who replied, I'm checking it out. See my blogpost at http://zvolkov.com/blog/post/2009/04/15/Learning-VI.aspx for account of my experience.