Why use icon fonts?
Just so we're all on the same page, I'll summarize the pros/cons of using webfonts to display icons.

Pros
Fonts are vectors, so there is no pixelation or blurring on high-resolution screens as there would be if the graphic was raster and needed to scale up.
The browser support is as good as you need it to be
Once the system is in place, using them is very convenient.
Arguably easier than spriting images.
They can be controlled with CSS, like the size, color, shadow, etc.
Cons
The icons will be single-color. There are some fancy (hacky) techniques for multi-color however, and modern trends and HIGs (human interface guidelines) suggest single colors anyway.