Mullvad is a great browser, especially as a default browser (for opening links) as it will clear all cookies / local storage every time you close it down. So it's ideal for random browsing.

Every time you open, it is like a fresh browser. It also brings a whole load of extra protections from the Tor project (such as reduced fingerprinting).

For sites you visit a lot, and want to stay signed in (like stacker news) then you should use a regular browser. Also some sites won't work, due to all the tracking protections.