One of the best site blockers I've seem. I enjoy the amount of options, the way you can set up barriers for yourself (like password protecting), allowing timers for some website but not all, a time block that can be different for each website, etc.
Not only I'll continue using this extension to stop opening reddit and youtube when I should be working, but I will also set up timers so I don't waste more than 5 minutes of my free time scrolling endlessly on twitter and hackernews.
I can recommend this to almost anyone, since all features are free, easy to understand and can fit all type of user case.
Great job.