At a largely Windows-based shop I installed Linux on my system and had Gnome set up with some fancy 3d-box transitions. I got some startled wows from my coworkers when they were helping me with something over my shoulder and I switched desktops.

However, I always found myself reducing the transition time bit by bit, until I eventually got rid of the transition. When I'm in the zone and coding I might be checking docs or some output on one workspace, and I want to switch workspaces and begin typing without the feedback delay. I already have the next 20 keystrokes planned out, and I'd rather be rate limited by my fingers than my WM.

You certainly want to eventually get rid of all the transitions when you've learned to use a WM instinctively, but for newbies they can provide valuable feedback.