It does what it says it does, and it does it well. That's all that matters. It has one of the best UIs of any extension I've used. It's feature rich and highly customizable, but easy to adjust. Quick to enable or disable on a per-site basis. All in all, it's a pretty seamless experience. I don't use it everywhere, but when I need it I NEED IT. Any time there's an issue (which happens with all software at some point) the team jumps on it and gets a fix out quickly. It is 100% free. There is no requirement to pay to get full functionality. Even so, I've still donated because it's just that useful. I've been using this extension for many years and will continue to use it as long as it's available.