When money overtakes morale it becomes Ubuntu. Since long Ubuntu has been trying to avoid the Linux identity. Its a good call from Stallman bringing out Ubuntu's real motive is/will be few years down the line.
Switched to Arch Linux since 2008 (that's when Ubuntu was spelt around the globe) and I'm happy about the decision.
> Can you recommend me a setup for using Arch as a desktop? Eg: which UI should I install?
xmonad is probably the best option.
> Do things like sound, video, usb, etc work fine?
USB works by default. I'm not sure why people even ask this anymore.
You will have to configure sound (easy, usually works by default) and video (not too bad these days) yourself.
Keep in mind that the Arch Installation Framework (an ncurses-based installer) has been deprecated, as of earlier this year. That means you will have to follow the Installation Guide[0] to manually set up the system from a live command line, Gentoo-style.
Switched to Arch Linux since 2008 (that's when Ubuntu was spelt around the globe) and I'm happy about the decision.