It copies a lot of Arc, but the core tab organisation features from Arc are significantly lacking. Last I checked (a few weeks ago), Zen didn't even have a keybind for pinning a tab. It fully keeps the Firefox bookmarks and prioritises those all over the UI. The Arc tab system is meant to entirely replace all of that. It just makes Zen feel very shallow in comparison. It's just firefox with some goofy Arc features mashed into the front without care.
Arc (macOS) is ridiculously good though. It's become difficult/impossible for me to use another browser happily the past few years. I wish they were focused on it instead of their mediocre AI browser project. They decided to claim Arc windows was out of beta when it's still vastly worse than the mac version in just about every sense. But at least they got the core tab management features locked down (from what I've heard, I don't have a windows machine to try it on.)
What are you going to do now that Arc development has stopped and The Browser Company is pivoting? (I'm also a big fan of Arc, especially the Air Traffic Control feature to keep certain sites organized into Spaces.)
Arc (macOS) is ridiculously good though. It's become difficult/impossible for me to use another browser happily the past few years. I wish they were focused on it instead of their mediocre AI browser project. They decided to claim Arc windows was out of beta when it's still vastly worse than the mac version in just about every sense. But at least they got the core tab management features locked down (from what I've heard, I don't have a windows machine to try it on.)