I have an Android phone and gave my wife the N9.

I don't need a new phone right now, but I'd be tempted to get an N9 for me too.

I'd say, the N9 is way ahead in terms of UI, but the Android market makes the choice easier if there are things you want and won't have on the N9...
Google sky map
Vncviewer
etcetc (don't care about all the fart apps, but there are really cool android apps)

On the whole, there's not all that much missing on the N9, and indeed after using it 3 days straight I was baffled at my Android phone, my fingers forgot how to use it (after having used it for a year...).

And I really like being able to cook up simple scripts on the N9 to do stuff.