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GNOME 3 is an easy and elegant way to use your computer. It is designed to put you in control and bring freedom to everybody. GNOME 3 is developed by the GNOME community, a diverse, international group of contributors that is supported by an independent, non-profit foundation.
SpecsUpdate
Pros
Pro Highly stable
Gnome isn't obviously devoid of flaws, but it's pretty stable - especially in comparison with the KDE Plasma Desktop, which can literally fall apart after installing upgrades (and show a considerable number of error messages) or for whatever reasons - after turning on the computer you can end up without (Plasma) desktop altogether, which I believe IS quite unproductive. It is also noteworthy that many other major desktop environments are based on Gnome, and among these are: Cinnamon, Pantheon and (now dead) Unity.
Pro All the major players in the Linux ecosystem have finally collated on Gnome
Red Hat default = Gnome
Fedora default = Gnome
Debian default = Gnome
Ubuntu default = Gnome
Opensuse default = Gnome
This doesn't mean the others go away, it just means there is a colossal community and industry backing behind Gnome.
The point whether or not it being technically the best option is now off table and irrelevant. It is now the de facto standard. Like it or not.
Pro Integrates with most Google Services
You can use your calendar, drive, contacts and most of Google services with Online Account option. You can show your Google Calendar events on the Gnome's default calendar app, Nautilus (Default file manager of GNOME) almost fully integrated with Google Drive and even you can read your PDF's with Evince (the default built-in PDF reader in GNOME).
Pro Easy theming
Changing the look (and feel) of Gnome Shell is easy, shell theme, icon, windows and graphical elements (gtk) individually for each user.
Mostly it's installing some packages or unpacking some archive to a themes folder and using selecting the new theme in e.g. gnome-tweak-tool.
There are a lot of really good themes on DeviantArt.
Cons
Con Full screen start menu
This may be fine if your screen is really small, but on a modern full HD desktop, it looks ugly and distracting. In addition to very ineffective display of items on screen - much more could be placed on one screen if there were less empty space around and between icons.
Con Default alt-tab behaviour is cute but extremely annoying for fast keyboard users
Con Longtime support is hard since every few years GNOME changes its own standards
Everytime something is complete GNOME breaks itself:
Icon naming changes almost every 3 years : once gtk icons were named stock_edit then gtk-edit then edit-edit and currently edit-edit-symbolic
- App icons change also every few years currently they get renamed to an android like scheme eg: org.gnome.Photos.svg instead of gnome-photos.svg however this breaks all common standards esp. since filenames on linux are case sensitive.
GNOMEShell extension also break on almost every release.
Currently Gtk3 has been stabilized however they are already working on GTK4 and 5 so in the worst case your desktop will need to run and support 4 GTK-toolkits at the same time.
Con Some settings are not where the user would expect it
E.g. it is not possible to change the keyboard auto-repeat delay or rate from the usual All Setting > Keyboard like, for example, in Unity.
Many settings are considered "tweaks" and require installing a separate utility to adjust.
Further still, some settings are buried in a dconf database.
Con Icon scalability and sorting
The icons in the "apps view" area don't have any additional sizes, the current ones are much too large to be effective for the screen space they use. Also, there is no native way to sort them in Gnome, only a very limited extension. Which means you're pretty much always better off using the search bar if you can.
Con Native Gnome dock isn't scalable
The native Gnome dock isn't scalable, which means if you want to change its size you have to download a customized theme for the shell and hope it has the appearance you want. Honestly again just like the icon issue it wastes way too much of the screen on high resolution monitors.