Recs.
Updated
Vivaldi is a Chromium based browser with its UI written with web technologies (HTML/JS). Vivaldi advertises itself as a "power-user browser" as it tries to bring features built-in reducing the number of extensions needed.
Vivaldi was founded by Jón S. von Tetzchner, creator of Opera browser and its CEO until before the switch to Chromium.
SpecsUpdate
Pros
Pro Tab behaviour can be customised
The order you toggle, open, close or clone tabs can be modified to match a workflow that best works for you. For example you can choose tabs to toggle in recent order so you can go back and forth between the last most useful tabs without needing to change their position on the tab bar.
Pro Built-in page capture
Vivaldi can grab a picture of the whole webpage or part of it and saves it automatically inside a note or as a file in your disk, or in your elected directory. But I have problems with images of full windows shown on monitor (using X Window System in GNU/Linux). Here I use system XWindow screenshots.
Pro Custom search engines
You can add as many search engines as you like. For example you can set up one for YouTube, one for Wikipedia, or whatever you want: you need only the URL of the search and it can be used from the URL bar (by prefixing it's nickname, yt
for YouTube for example).
Pro Can be used to keep notes
A notes panel allows to save notes from webpages and can include screenshots for reference and have tags and organized in folders to help manage them. Thumbnails are too small and Notes do not have separate page in settings, but it should, there are a lot of things to improve.
Pro Updates via dialog box
Unlike most modern browsers (but like most browsers of yesteryear), Vivaldi gives you a dialog box when an new version comes out; it doesn't just update silently in the background. The dialog box tells you about the changes that have been made, and lets you chose when you want to update.
Pro Built-in ad and tracker blocker
Vivaldi has a built-in blocker that allows you to select between blocking just trackers or both trackers and ads. With customizable blocking list sources, good performance, and support for all the standard blocker list features you find in ad blocker extensions (with more to come), you might not need an ad blocker extension at all.
This also comes in handy on Android, where Chromium/Vivaldi doesn't support extensions.
Pro Allows navigating to the next page without searching for the link
A feature called fast forward puts a dedicated button before the address bar that is designed to help you navigate to the next page of a multi-page article, forum thread or search results without having to hunt for the link.
Cons
Con Advertisements in the bookmarks
By default: Vivaldi has a number of websites (such as Amazon) already bookmarked. New bookmarks may be added to the speed-dial when the browser updates. These bookmarks can be deleted, same as any other bookmark, but that will not stop new bookmarks form being added.
Con Some non-optional telemetry
According to its privacy policy, Vivaldi sends an approximate location (country or major city), randomized ID, version, cpu architecture, screen resolution (to know what screen sizes to test on) and time since last message every 24 hours (to know amount of active users).
Con Not available on your phone/tablet
Vivaldi is currently only available for desktop operating systems (Windows, Linux, Mac). Though the developers have already said that they plan to release it.
Con No silent background updates
Unlike most modern browsers, Vivaldi doesn't have the option to update silently in the background. It gives you a dialog box when an update comes out. Worse, the box doesn't warn you that not updating the browser could lead to security risks. That could be pretty bad for your average joe, who doesn't know computers that well.
Con Proprietary
While Vivaldi is currently available gratis (without monetary charge), it is currently not fully libre (meaning that it does not allow users to view the source code used to create, to modify that code, or to redistribute modifications) and is therefore neither free nor open-source software.
The C++ source code however is open-source under a BSD license and can be downloaded and browsed from here.
The UI code though is not open-source, but it's easily readable as it's HTML, CSS & JS. Modifications can be shared as their forum even has a dedicated section.
Recommendations
Comments
Flagged Pros + Cons
Pro Notes
A notes panel allows to save notes from webpages and can include screenshots for reference and have tags and organized in folders to help manage them. Thumbnails are too small and Notes do not have separate page in settings, but it should, there are a lot of things to improve.
Pro Web Panels
Web Panels allow for easy access to any site from the side panel. They are useful for reading two websites side by side or for chatting (i.e. Facebook) and surfing at the same time. Panels can be hidden when not in use.
Pro Compatible with all Chrome extensions
Since Vivaldi is built on Chromium, the same base as Chrome (among other browsers) is built on, it was possible for Vivaldi developers to allow Chrome extensions to run in their browser.
Pro Customizable UI and colors
Vivaldi can change the colors across the browser and has the option to change the color automatically depending on the page. Also, page loading animations are available in the address bar.
Con Sponsored bookmarks
Vivaldi has a number of preinstalled bookmarks, like Amazon. On some occasions, new bookmarks have been added when the browser updates. All of these bookmarks can be deleted, same as any other bookmark.
Con Not available on iOS/iPadOS
There is an Android version of Vivaldi, but no iOS/iPadOS version yet. iPhone and iPad users are out of luck for the time being.
Con Not available on the iPhone
There is an Android version Vivaldi, but no iOS version. iPhone and iPad users are out of luck.
Con Comes with many Ads
After installation the first thing you have to do is to remove all the default bookmarks and quickdial links which is really annoying. There is more minor stuff like the default search provider or your start page things that could be easily managed with a wizard at the first startup.
Out of Date Pros + Cons
Con New and buggy
Still working out a few kinks, not entirely optimized yet so it can be a little slow or resource intensive. The latest versions have much improved performance though.