I use this every day, it's invaluable for debugging websites as multiple users (e.g. where users interact) and Chrome has nothing like it - keep up the great work!

Best thing since sliced bread. You can create tons of independent containers. Especially useful with sites like Google news where I open it in one container then every news item in its own container. When I am finished reading the item, the container and all its cookies disappear.
Super for multiple logins on a single site simultaneously.

Beautiful security tab feature.
I recommend not using Auto mode, but using Alt+C to manually open tabs when needed.

Definitely go for anyone who using firefox. Convenient, easy to manage.

Best extension if you manage Office 365 accounts

An absolute must-have for day-to-day browsing.

Super useful. I love that I can browse Amazon/eBay while being mostly anonymous.