It's a good idea. I have noticed that max desktops for me is 3 because after that's it's just faster to use main menu, but this could change that.

Best of all would be if the widget would be rather big and you could use pictures for the buttons that change the desktop. Example picture of the desktop or album to show that the desktop is about music.

Even better could be if the widget would take picture of the desktop last time you visited it. Like browsers bookmark thumbnails in browser, but i'm not sure if it would work in real life.