Bootstrap grid system was confusing for me the first time I used it. Recently I did some research to change the old CSS framework that I usually use for my web projects. After long searches and tests I decided that Bootstrap 3.0 it will be the best for me. I’m still not fully happy about Bootstrap, mainly because the fact that the menu does not accept multiple menu levels, but I have did some changes to make it work as I want.
As I said, the problem which I encountered with Bootstrap was the grid system. Although it is something logical, it was confusing for me in the beginning and it took me some time to understand it so I can benefit the maximum of all features.