The browser is currently in Technical Preview release, meaning it’s still a little buggy, and a few features (like the sidebar email client) just plain aren’t working at the moment. But having played around with everything that is functional, Vivaldi seems like a slick, powerful internet-browsing machine.
The basic UI is reminiscent of old Opera: an address bar along the top, and a search engine in the top-right, a move that eschews Chrome’s universal bar. Along the left, you’ve got a sidebar, which has tabs to let you flick between a Notes page, downloads, contacts, emails, and bookmarks. You get to Settings via a button in the bottom-left.