The UX is amazing if you ignore gnome/kde etc, which are just imitations of windows and mac. I'd say the true linux UX is in tiling window managers. Just like the terminal and vim/emacs, tiling WMs have a steep learning curve and an amazing payoff where the computer becomes an extension of your will, rather than something you fight. I really recommend you try them.
That being said, they don't look pretty, but they make me so productive I just can't go back to anything else.
I disagree that tiling WMs necessarily have a steep learning curve. From experience I claim: Anybody can learn to use a WM like xmonad in its stock configuration in about 30 minutes, and be proficient enough to have a significant boost in productivity in a day or two.
You're right that it's not necessarily steep if you're used to using keyboard commands. But if you're used to doing everything with a mouse it might take some adjusting
That being said, they don't look pretty, but they make me so productive I just can't go back to anything else.