Underscores is a WordPress theme starter that save your time a lot. It is more effective way on creating WordPress thheme rather than creating it from scratch. So, you can focus on its functionality and design, including composing graphics and CSS. Even implementing jQuery.
There is no doubt using this tool because it is created under Automattic experiment. The advantage using Underscores theme starter is the code always updated by contributors on GitHub. As in Underscores homepage, the theme has a just right amount of lean, well-commented, modern, HTML5 templates, and so on. Jump to underscores.me for details and see its awesomeness.