Well the UI is much more than a launcher. The N9 / MeeGo had the most redefined and brilliantly designed user interface on smartphones, both visually and functionally. Miles ahead of current-gen Android, for example. IMO It's the only interface that had the same 'magic' of iOS through simplicity, yet it was way more powerful. Here's couple of nice animated examples to get a glimpse of it:

http://harmattan-dev.nokia.com/docs/ux/pages/PB_Opening_and_... http://harmattan-dev.nokia.com/docs/ux/pages/PB_Backstack_an...