First of all, I want to say that I like the vibrant colors, small size, and checkable buttons. Smaller (and JS-less) CSS frameworks is something that I've been crusading for for years now. Secondly, I'm the creator of Min ( http://minfwk.com ), a fellow small CSS framework. Min is only 995 bytes - 5 times smaller. It also is more widely used, has feature parity with Bootstrap through the Min Bootstrap plugin, support…
Nuts to those calling bad taste: if I had a competing framework I'd be making it part of the conversation, too. Besides being tiny, how does Min stack up against Picnic, owenversteeg? I expect a bias opinion, don't worry ;)
Personally I think Min's largest advantages over Picnic are:
* more features (button sizing, messages, input addons, 12-column grid instead of 6-column grid) * vastly better browser support (not only does Min work on IE5.5+ but also it is tested across hundreds of browser and device configurations before each release) * Unprescriptive - it's incredibly easy to override Min's styles and turn it into something else while still making use of Min's extensive testing and features. With Bootstrap you have to use !importants and strange selectors; with Min overriding things is easy as pie. * LESS/Sass versions * An icon-set that works out of the box