It's pretty fast these days, the UI is good, has a lot of great extensions and privacy features.
I use Brave at work to have a better chrome-based experience with gsuite. It's also a fast, excellent browser with good privacy features, built-in ad/tracker blocking and for the time being seems to be user-not-revenue-first.
But using a non-free browser feels like a trap to me. Just as what happened with Internet Explorer, Chrome, and Netscape before, being the middle man between the user and the rest of the internet is just too tempting for any company not to try to leverage for their own advantage.
FF hasn't been always perfect, but for 20 years now they have made a browser that didn't have a shady corporate agenda. It feels like the writing is on the wall though. Even people I know who care about FLOSS are using Chrome as their daily driver these days.
Mozilla is great and I hope they continue to focus on building a best-in-class browser.