In my opinion, the only great thing about Bootstrap is the grid system and form styling, the rest is just useless cruft. As a front-end developer, I see the value in Bootstrap and I have used it before, but when installing it as a Bower component, it makes it harder to filter out the crap you don't need like button styling, header styling and other stuff Bootstrap includes that just bloats your CSS. To me, I find Bootstrap TOO opinionated, I spend a lot of my time overriding styles than I do setting them. In the real world unless it is your own project, you are being given designs and fitting the style of a PSD file into Bootstrap can be more trouble than it is worth.
These days I actually use Foundation by Zurb which I think is arguably one of the best front-end CSS libraries out there, it allows greater control and offers some awesome Javascript components. Not only that, it has a great grid system like Bootstrap, but it is by far, the least opinionated and most powerful front-end library out there.
Cudos for trimming the fat and offering an alternative for those who use Bootstrap. My only nitpick is those bevelled buttons don't look very nice and the classes for the grid system using fractions might be a little confusion for some who are bad at maths and fractions (like me). I prefer having the option of putting the number in the class like in Bootstrap: col-md-6 as opposed to using a class called "half"