Coming from Firefox, it's got a very nice default UI - I love the loading animations and such. It seems easy to customize, though puzzlingly the icons don't see

Coming from Firefox, it's got a very nice default UI - I love the loading animations and such. It seems easy to customize, though puzzlingly the icons don't seem to be themeable even though colors, address bar appearance, etc are - which is a bummer because the default icons are ugly Windows 8-style/Metro things. Also, it seems to be implementing its own scrollbars that are stylized differently than everything else on my computer. Firefox also uses my GTK theme for things like checkboxes, etc (right out of the box), which is pretty cool. Vivaldi's doing some cool things, but it's still got a ways to go.