It's noticeably faster and just as stable. You now have the option to use up to 5 Content Blockers rather than just the one in the non-beta and the option to use DuckDuckGo as the search engine has been added. I'd recommend switching to it now as you can still retain the stock version to use simultaneously.
The biggest negative is that you can't import bookmarks and settings from another browser even on the same device or backup your current settings to restore after a reset or on a new device. You can save the bookmarks as you can in the stock version but still have to set up logins one by one again after a reset.
As far as I can tell Samsung ignore feedback or feature requests as usual.
It's such a shame they haven't included the chrome like feature were you can log in and access your bookmarks from any device.
How is the iris authentication for logging in to websites?. Did it all still work ok?.