I just tried to swap in the new font-based glyphicon icons over the top of the old image based ones. First of all it's not a clean swap, because the class name

I just tried to swap in the new font-based glyphicon icons over the top of the old image based ones. First of all it's not a clean swap, because the class name structure has changed. Secondly, the font glyphs seem to have totally random positioning, so depending on how you use them you'll need to tweak the css for each one (or certainly groups of them) so they align properly with the text/button/whatever. I reverted, and dropped in Font Awesome. It was as simple as changing one line of css if you use the CDN, done. No tweaking required, and there's load more to choose from.