This depends a lot on how well supported your hardware is. I run Linux Mint (MATE) on a Thinkpad T430 and have had 0 issues with displays, sleep, battery life, you name it.
Not having issues means that you arrive at the hardware (which you may have never seen, e.g. at a customer's site), plug the wires, and it works immediately.
More importantly, not having issues means that you can rely on being able to just plug the wires and have it work, and that you don't have a risk of being unable to make it work immediately even if you forget the right invocations and are offline and can't look them up.
How does it work immediately? How does it know of I want to clone or extend the display? If I extend, do I want the same resolution on both screens, or different? You'll have to set that somehow, and whether it's a GUI or a CLI tool doesn't matter.
Forgetting the invocations aren't really an issue anymore either, my shell (zsh) has autocompletion of xrandr outputs, modes and resolutions.
Requiring a CLI to connect a monitor/projector is a UX fail.
None of this is new, and the whole point of this discussion is that Linux desktops are much better than they were ten years ago. It is that old state that many folks have in mind when criticising Linux distros' usability. It's just not a very interesting discussion to have.
It even worked on the first try from the X220's DisplayPort through a DP-to-HDMI-cable onto a TV.
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I've never had to use xrandr or any command line tool to select displays – on Xubuntu, there's this little graphical dialogue: http://netupd8.com/w8img2/xfce-mini-displays.png that pops up (or you can force it to show by hitting that key on the Thinkpad keyboard with the picture of an external display).
OTOH, I did just a month ago for the first time actually use xrandr, but this time it was because I wanted to write a script that set my windows and monitors up "just right" for how I like it when I'm at the office. I love how easy Linux makes it to do that stuff when I find I do want something automated.