I still use N9 as my primary (and only phone).

My reasons are:
I don't want to surrender to Android
Both WP and iphone are not even considerable (surrender to MS or Apple).
It has all what I need: skype (trying to get rid of it but no use), email, web, phone, gtalk, messages, basic document viewing and basic games.

Yes it's aging, becoming slower and sluggish but so far there is nothing that can replace it fully (for my use cases) :/