What are some alternatives?
When comparing metro-bootstrap and Bootstrap, you can also consider the following products
Metro UI CSS - Metro UI CSS a set of styles to create a site with an interface similar to Windows 8.
Foundation - The most advanced responsive front-end framework in the world
Semantic UI - A UI Component library implemented using a set of specifications designed around natural language
Material Design Lite - Material Design Lite Components in HTML/CSS/JS
UIKit - A lightweight and modular front-end framework for developing fast and powerful web interfaces