The Vivaldi browser is the result of some of the older Opera developers. It's based on Chromium, and it's aimed at the power user group, similarly to the old Opera, where you had a gazillion options to tweak to your liking. My mom used Opera btw, and she was far from a power user.
I switched to full time Vivaldi use last week, when my Firefox startup become so slow, that even I, who was a Firefox user ever since 1.5, said fuck it, this is too slow for me. Firefox was never slow to me, but lately it took me about 1 minute to start. And the solution was to switch because this was without extensions.
Here are my 5 reasons I switched to Vivaldi...
5. A browser for powerusers
Vivaldi is like a browser for sandbox! So many possibilities given, yet, if you don't want to tweak anything, you don't have to! It's simple. Just like KDE! Yay! Power to the people! Hahahha
There are so many small things you can change, it's awesome. And the browser has sensible defaults for people who just want a fast browser.
4. It's fast
Talking about speed. Vivaldi is fast both for startup time (I accidentally wrote fastup time at first, hahah). I use dozens of tabs all the time, and switching tabs is so fast.
Tons of things, like downloads, history, etc in the sidebar. However the best feature, that you can load webpages in the sidebar, basically as another tabbar! Very handy for social media sites, I already started to use it for mastodon! Or I could use to follow Bryan Lunduke's twitter! So many possibilities...
2. Small things
I was surprised that Vivaldi has a screenshot tool, that you can use to capture page, even fully or just a selection.
It's a great tool for trolls to use for those nice twitter screenshots! Yay!
It's kind of hidden on the bottom bar, yet it's an interesting feature. These actions only apply to the current page. You can apply different effects, like black and white, sepia. Or you can distort image, but you can also obscure the whole page (which is a nice blur effect over the page).
My favorite, and I think useful is highlight focus, with it you can focus on text that you selected with mouse. Although it might not work in some cases. Other useful filters are the reader view, which eliminates all graphics from the page, so you can read an article without interruptions. And since I am kind of oldschool, you can turn on fonts monospace, and enjoy your favorite monospace font for reading.
These filters can be combined, so you can use more than one at a time. I cannot wait for it, where they take this feature. I'd like to see group feature, where the user can define filter groups and save it for later application.
Adjust colors of the UI, and apply it to time of day. Really great feature if you spend a lot of time in your browser.
Keyboard shortcuts and mouse gestures
Keyboards and mouse has a tons of features, and that's good if you like shortcuts and mouse gestures.
1. Vertical tabs!
I have to say one feature every browser ought to have in the 21st century is vertical tabs. Why? I think most people now has widescreen monitors, and a horizontal tab bar just take up space, that we could use for using and reading the web page. What's more impressive that you can position your tabs whereever you like, even to the bottom! I think vertical tabs are seriously great feature, and you must try it with Vivaldi. It also doesn't take up space, since the extra sidebar stuff can be switched off with a click or shortcut.
The only other browser that has vertical tab options built in by default is qutebrowser which is a seriously great little web browser, for technical people (it uses vim-like shortcuts for everything).
Also note: I contributed to a qutebrowser kickstarter in the past few years.
The Vivaldi browser is downloadable from their website for Linux, OS X and Windows.
For Linux users, always check your distros repository.