Xfce is a low resource user friendly desktop environment created for UNIX-like operating systems.
Ranked in these QuestionsQuestion Ranking
Pro Low system resource consumption
For users with netbooks, tablets and older computers where not a lot of system resources are available.
Pro Classic and familiar
Xfce works very much like the classic Gnome & Windows desktops, taskbars (panels) and desktop icons, letting you get your work done without being frustrated.
Xfce embodies the traditional UNIX philosophy of modularity and re-usability. It consists of a number of components that provide the full functionality one can expect of a modern desktop environment. They are packaged separately and you can pick among the available packages to create the optimal personal working environment.
Pro Highly customizable
XFCE offers plenty of settings, and even things like theming XFWM is a simple task (it's just a handful of images.)
Many possible permutations of window colors, borders, fonts, etc. Compositing can make it look downright sexy.
Pro Designed for productivity
It loads and executes applications fast, while conserving system resources.
Pro Rock solid stability
XFCE will NEVER be the cause of your crash.
Pro Works on a wide variety of platforms
Xfce can be installed on several UNIX platforms. It is known to compile on Linux, NetBSD, FreeBSD, OpenBSD, Solaris, Cygwin and MacOS X, on x86, PPC, Sparc, Alpha...
Pro Adheres to standards
A priority of Xfce is adherence to standards, specifically those defined at freedesktop.org allowing for interoperability and shared technology for X Window System desktops. This interoperability is particularly significant for users looking to, e.g., run alternative window managers.
Pro A true UNIX Desktop Environment
XFCE adheres to the UNIX philosophy, which means it strives for being modular, minimal and expandable. This makes it very much customizable. You can make it as minimal as you want and as heavyweight as you want depending on the features and modules/plugins you use.
Pro HiDPI display support
It has HiDPI support, but requires adjusting settings. In Settings Manager → Settings Editor → xsettings → xft DPI can be adjusted. Setting it to around 180 should work well for "Retina" screens.
Pro Window manager (XFWM) is a compositing WM by default
By having a compositing WM as the default WM makes way for a lot of visual tweaks and tricks that can and do make XFCE look great. You can adjust the transparency, shadows, borders, etc. and many other advanced tweaks are also available.
Pro Well defined Session Manager
Con Looks ugly out of the box
Out of the box, XFCE is the one of the ugliest if not the ugliest DE out there. It definitely can become the most beautiful and gorgeous DE's after a bit of tinkering and theming, but the default theme is not that good.
Con Looks dated
It just looks like a 20 year old desktop in its stock form. However, it is possible for you to to give it a more elegant look using themes, icons and other customizations.
Con Screen tearing issues
The built in compositor for XFCE does not handle vsync, meaning that it does not address screen tearing for those with Intel integrated graphics. A third party solution will have to be used for those that do want vsync such as using Nvidia proprietary drivers to handle vsync or installing a third party compositor such as compton.
Con No HiDPI support
Since Xfce is still based on GTK2 there is no HiDPI support (scaling UI elements).
Con Missing some basic functionality for a desktop environment
Xfce will miss some essential functionality like a file-archiver or a polkit-client so you have to find alternatives for those applications (eg: by stealing thee from MATE or GNOME, however this adds additional dependencies that will bloat Xfce).