Screen's primary payoff is when your connection to another machine goes down a lot for whatever reason. A good wm can handle the multiplexing better but they don't restore context like screen.
I love this! I use dtach (with dvtm) instead of screen, but it's serves the same purpose. I'll be working at my desk and then have to head to a meeting (with my laptop) to another floor. My ssh connection will drop but once I log back in I just need to reattach and I'm right where I left off.