icons as font in CSS

I would like to ask those of you who do do web development professionally - how do you prefer to use icons in your projects? I mean it seems that CSS frameworks are getting more and more popular and some of them use icons as simple images (mainly in PNG format) while others adopt a way of creating fonts that use icons instead of the font's characters. I find this solution clever because it allows you to scale icons (because they are vector), change their colors and do other cool things. But I am not really a web design guy and I wonder if there is any downside to using icons this way (formatted as a font).

I would appreciate your thoughts on icons as a font and maybe you can recommend even a better way to deal with icons in web layouts. Thanks in advance!