It does exactly what it does: blocks me from going into distracting, time-wasting websites. I needed that for my Firefox and this is very helpful. Highly recommended.
Easy to use add-on which really helps to stay focused while working. It has two modes: one disabling access to blacklisted websites and other enabling access to only whitelisted ones. I really like the minimal approach enabling you to use it without any additional stuff like visual customization and other unnecessary options. Does what should do really well!
