It's actually rather good
I'm on the darker end of the Sceptical Curmudgeon Disorder Scale, but I have been impressed by Vivaldi. I came to it by being utterly sick of Don't Be Evil¹, fed up with Firefox, and was hooked by (of all things) the fact that Vivaldi treats zoom scales on a per-page, not per-domain basis: in other words, I can zoom a specific page of (say) a Dynamics instance without every other page belonging to my domain also scaling to the same degree. A small thing, and an absolute blessing.
As I am fond of telling imbeciles¹: the devil is right there, in the detail, every single time.
¹ Cowboy IT "professionals"; senior management; cretin politicians; take your pick ...