This browser is not meant for general use. It only exists, because the Opera developers had some ideas for the user-interface, and wanted their users' feedback. If you want a browser that you can use day-to-day, something with bookmarks and security updates, look elsewhere.

The usability is not the best since the left and right bar take up space and there is no way to resize them.

The Opera folks came out with a browser as an experiment - and then they essentially abandoned it. It really was great, but since they never planned to support/update it and it's closed-source, it's not recommended.

Due to the way the browser is built, it does not support Chrome extensions even though it is Chromium based. Opera extensions are not supported either.

There is no Adblocker like in the original Opera.