Recs.
Updated
Specs
Pros
Pro Customizable
While the default style is not bad at all, Materialize also gives developers the ability to customize it and fit their own style, while still keeping in line with the Material Design philosophy.
Along with the CSS files, designers can also download the SASS files which can be edited and compiled.
Pro Opinionated
Material design is very opinionated on how design elements should behave and look. The basics of which revolve around certain visual elements (physics, space, momentum and light) which are used to create specific UX elements.
This is very helpful because it creates a consistent feel without making every design look the same. This can be seen in Materialize too, where each element may be customized but still it keeps the consistent look of the material design.
Cons
Con Refuses to use the flexbox model
Even though Materialize states that it only supports IE10+, which supports flexbox quite well, with prefixes, Materialize has refused to use Flexbox.