Over the past year I've seen a big increase in projects that demand "Twitter Bootstrap experience" and devs claiming that they are "versed in Twitter Bootstrap." My colleague Bernard has even started seeing it in his intern applications:
People applying for internships sure like to list Twitter Bootstrap on their resume these days. >.<— Bernard Yu (@thebestsophist) April 1, 2014
Newsflash to all you kiddies out there: Bootstrap isn't a language that you know. It is not a skill that you have acquired. In fact, if you feel that Bootstrap is a noteworthy "skill" to have, it's going to make me question the actual depth of your knowledge of front-end development. Bootstrap is a tool to use and don't get me wrong, it has it's uses. If the most important thing is a basic design and a quick deployment, Bootstrap can be really helpful. It's got snazzy buttons and neat animations and you can make all that stuff happen with a minimum of effort. Sweet!
Claiming Bootstrap as evidence that you "know" development is like claiming that changing your oil means you "know" automotive engineering. Sure you can navigate your way though basic things, but this doesn't mean that you have an understanding of the mechanisms at work - and that's what's truly important.
Development involves testing of your problem solving abilities - how can I make this thing happen in the most efficient way? You can't do that if your knowledge of HTML/CSS/JS consists of plug-ins and templates. So break out of the walled garden of Bootstrap "skills" and make something happen from scratch. Your brain (and future employers) will thank you.