It's not perfect but IMO it's better than Chrome. Logging in to my Gmail account in Firefox doesn't do the same obnoxious stuff it does in Chrome (changing browser profile, start synching lots of stuff with Google).

Of the problems I've had with Firefox, some of them are actually due to it being _too_ privacy focused, and not having good UX explaining why common operations don't work as expected. For example I couldn't save a file onto my computer and was pulling my hair out until I did a binary search through every version of Firefox, found the first version that didn't work, read deep into the patch notes, and discovered that I needed to set the magical flag of dom.ipc.plugins.sandbox-level.