I like that it's available for free, so you don't have to pay money just because you want to use some of their themes/components. It can be difficult sometimes when working with CSS but once you figure out what is going wrong, then everything works great! You should definitely check this library out if you are looking into creating your own web applications or even using them in other projects. We're building an application where we needed to create our own user interface elements (such as buttons). The Material Design Lite was very helpful since they had pre-built versions for us to modify and customize however we wanted.