I've been using it a fair bit recently, and don't come across issues very often at all. It doesn't support Webext extensions (there's a bug in the tracker to do so, but it hadn't got much attention in years, last I looked) but it does have a built-in adblocker that works reasonably well on a decent percentage of sites, so it's not all bad.

Edit: some particularly JS-heavy sites do peg my CPU pretty badly, so it appears that the JS engine isn't as snappy as FF/Chrome, but sites that use either don't use much JS, or that use have optimised the use pretty well are fine. Airbnb was a notably bad case that I spotted last week.

"Power and privacy to the people. No need to dig into your security settings. Fierce privacy is our default."

- Firefox on a recent update. You know, a browser that defaults to Google search and having search suggestions on. I know I'd have a couple privacy settings to change.