> NO. It is NOT a good thing. When it comes to visual design, things are supposed to look different. Twitter is meant to look different than Facebook and facebook should not look like Amazon. That's how you create mind-space . Bootstrap kills that - they all just look the same.
It depends on your goal. If you want to make an application that people use all day, having a unique UI is probably not a win. If you used Netscape back in the day you can use Chrome today and not have trouble. Consistency itself can be beautiful.
If you're making a marketing site, then your designer can go wild (as long as everything is being tested for effectiveness).