The N9 was a regrettable purchase for me. I even feel that Nokia owes me, all these years later!
Paid a lot for the 64 gig N9. Soon after Nokia abandoned the OS, and I felt ripped off.
I remember the flash refused to stay off. I would disable flash for a photo, but next time I used camera the flash was back on. This was enough to move to a phone that remembered the flash setting.
Years later I tried to start my N9 but it was demanding a password that I didn't know. Some kind of recovery password I never knew I had set up. There was no way I could find to reset the phone even to factory settings. It's basically bricked with no way to restore, so I couldn't even sell it as a working phone.
Android have copied some elements of this but it's nowhere near as simple!
The hardware was fantastic as well. I dropped mine several times without a case and it never broke.
The TI dac sounded great with my Sony XBA-3 iems I had at the time.
I did hate the USB port cover though. And hated that they didn't have a dedicated camera button like the N8 and n97.