> but I find all this emphasis on 3D pretty annoying, a waste of resources
90% or more of silicon real estate of graphics chips these days is dedicated to 3D. Using that to display 2D is actually faster and works better than using the 2D hardware. This whole thing is not about 3D effects, 3D for CAD or anything like that. It is about using the hardware so that the regular desktop works smoothly.
For instance, I use compiz but I do not enable any of the fancy 3D effects (e.g. wobbly windows, workspaces on the cube), because they are annoying to me. However, windows move better around the screen with compiz (because it's using 3D hardware to draw them), zooming is better, small objects are displayed more precisely (just look at the workspace switcher), scrolling is faster, CPU utilisation is lower etc.