Happy N9 owner here since it launched in Sweden, although I also use a Galaxy Nexus running Paranoid Android now and then.
Both OSes have their respective strengths but as for multitasking, MeeGo on the N9 wins hands down. Swiping away the app to the side moves you out of it, swiping down closes it. Side swiping while in the launcher moves you between its three modes (notifications, app icons and minimized windows). All of the movements are accompanied by (mostly) smooth animations that enhance the effect. The spatial GUI is simple, easy to learn, efficient and highly addictive. Going from the N9 back to Android is like switching from quill pen and paper to hammer and rock.