Requires Node, Ruby, Sass and Gulp.
Ranked in these QuestionsQuestion Ranking
Pro CSS vendor autoprefixing
Starter Kit includes Autoprefixer that takes care of vendor prefixes.
Pro Sass support
Since a lot of web designers these days don't use the plain old CSS, instead they use a CSS pre-processor (like Sass or Less). Thanks to Sass support web designers can easily add GWK to their workflows.
Pro High PageSpeed Insights performance score
Since the base skeleton provided by the Web Starter kit is authored by Google itself, it's pretty much understood that the template is optimized to the max, for performance. If you test a site (on Google PageSpeed Insights) built by the GWK you can be sure that it'll always achieve a very high score.
Since most of the websites that are currently being built (or any website that was built after 2012) are responsive, a 'scaffold-ed' website skeleton without any responsiveness would be pretty useless.
Pro Includes a gulp build script
If you use the Gulp build system and are familiar with its environment, you can directly use Web Starter Kit's Gulp build script to build your next GWK based project.
Pro Performance optimization
Pro Google-friendly style guide
Pro BrowserSync for synchronized browser testing
Pro Live browser reloading
Helps to build website faster by refreshing the page automatically as you save the source file changes.
Pro Built-in HTTP server
In case you want to try out your shiny new site on your mobile phone or another PC. Just type in the command
gulp serve and load up the provided server address from another device to see how your website looks and performs.
Pro Yeoman generator
There's a Yeoman generator for Google's Web Starter Kit available. To install (requires Node, Ruby, Gulp, and Sass):
sudo npm install -g yo generator-web-starter-kit cd project-root-directory/ yo web-starter-kit npm install gulp serve
Con Can't be used with Less
The framework CSS is built on Sass, which adds dependencies to the build chain. There's no option to use Less.