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 Add websites as web panels for easy access
You can add sites as panels for easy access them. It allows reading two websites side by side with a simple click on the panel button. Useful for social networks, like WhatsApp, Telegram, Facebook & Twitter. Panels can be hidden when not in use.
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 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.
The feature can also be accessed with a shortcut (default Ctrl+Spacebar) or by hitting the spacebar at the bottom of the page.
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 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.
Cons
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.
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 In development, as such there may be several important features that are implemented badly, non-consistent or illogical
Clear example of such feature is Oldpera-like image blocking. Enabled/disabled status isn't synchronized between tabs, does not stay consistently on or off, and is not merged with browser content settings. So, you cannot (like in old opera) disable images globally and enable them with quick click only when you need to see them on current page - global disabling requires going into browser content settings, temporary enabling requires the same, show images button does not override them.
Another example is support for chrome extensions, they currently do not show their own menu when clicking on extension icon in toolbar, there's only Vivaldi's standard options.
Con No option to open saved tab stack as... tab stack!
You may save a tab stack, but you can only open them as separate tabs. Interesting that when you save session with stacks, you'll be able to open the stacks with inner settings of page tiling (size and zoom) as well. Contradiction worth of shame.
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 No automatic silent background updates, except on macOS
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. The box doesn't warn you that not updating the browser could expose you to security risks, which could be pretty bad for your average joe, who doesn't know computers that well.
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 Same security vulnerabilities as Chrome
Vivaldi uses the same browser engine as Chrome, meaning it has the same security-vulnerabilities as Chrome. Chrome is a big target for hackers (being the most popular browser in the world), and a vulnerability for Chrome will likely also exist in Vivaldi.
Recommendations
Comments
Flagged Pros + Cons
Pro Includes tools for annotating web pages
A notes panel allows leaving notes on webpages and can include screenshots for reference and have tags and organized in folders to help manage them.
Pro Manages bookmarks well
Vivaldi has an excellent bookmarks system. Bookmarks can be easily accessible via Speed Dial, side-bar, bookmarks bar, quick commands. No more messy bookmarks bar is needed and location bar suggestion is improved thus!
Pro PC Cross-platform
Vivaldi is available on Windows, GNU/Linux and macOS, so it covers the most used PC operating systems.
Con Extensions are lacking hotkey functionality
You can set your shortcuts at vivaldi://extensions, but they do not work.
Pro Customizable UI
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.
Pro Ability to search through settings, history, open tabs, bookmarks in one place
A feature called Quick Commands (accessed via Ctrl + Q) allows quickly getting to settings, history, open tabs, bookmarks with incremental search.
Pro Built for power users
Vivaldi includes lots of niche functionality such as the ability to move tabs to any side of the screen, turn images on and off, or render pages with monospace fonts.
Pro Tabs can be stacked
Tabs can be grouped under a single tab to easily keep track of all open webpages.
Con Still in beta
The browser can often be buggy, many features, like the built-in email client, aren't there yet, etc.
Out of Date Pros + Cons
Con Not available on your Phone/Tablet
Vivaldi is neither available on Android or iOS.
Con No automatic page translation
Unlike Chrome, it doesn't automatically translate pages that are not in your language.
Con No built-in adblocker
Unlike Opera (but like most browsers), Vivaldi doesn't have an adblocker out of the box. You'll need an extension, if you want Vivaldi to block ads.
Con No PPA yet for Linux
Can only be installed by downloading the .deb files ... it needs a PPA to remain up-to-date.