I took two attempts to get the hang of Blender but the UI was so alien I gave up. Maybe I'm going to try a 3rd time because Blender is just such a powerful tool, but I'm not doing 3D full time so it's difficult to justify 3+ weeks learning.

For casual 3D work, I've always been a big fan of SketchUp, but there's nothing like it for Linux. A couple years ago I tried to run SketchUp via wine which to my great surprise almost worked, but when I wanted to save my model it crashed :(