Vertical tabs.

Comparatively, horizontal tabs strain eyes tremendously. It also reduces page display (unless you know some Asian websites that are scrolled horizontally).

Most users are on 16/9 screens with an horizontal task bar, and don't ask for vertical tabs... They are out of their mind! This is madness! Madness!

Veritabs doesn't work. Sidewise is but it's an awful experience.

I finally moved from Opera 12 to Opera 23, and I really really miss vertical tabs (and integrated email client).
So that's good to hear !

Last time I checked Chrome, there was a service running in the background, transfering data both ways, and the browser wasn't even launched... More than a browser, a Big Brother.