It's still at the prototype phase and the GNU/Linux port is only experimental, but a crowdfunding campaign was started a month ago to put full-time development into getting a stable and polished version! It got extended for one last week:
https://www.indiegogo.com/projects/next-browser-nix-support
To Emacsers and Lispers looking for a (Lisp) hackable browsers, feel free to join and support the adventure!