Bootstrap 2.x的文档中这样说：

Bootstrap doesn't include responsive features by default at this time as not everything needs to be responsive. Instead of encouraging developers to remove this feature, we figure it best to enable it as needed.

我觉得很有道理，但Bootstrap 3.x却变卦了：

Bootstrap automatically adapts your pages for various screen sizes. Here's how to disable this feature so your page works like in this non-responsive example.

经过我的一些实践，我觉得Responsive有点鸡肋，它的效果只能是让页面在移动端达到“凑合能看”的效果，远远达不到专门为移动端设计的水平。你要真以为能够“一次编写到处运行”，你就输了。

我认为还是要将PC端和移动端分开来设计，移动端也有类似Bootstrap的Ratchet，使用也很方便。