The passport has definitely made it feel a lot realer than the (admittedly lovely) citizenship ceremony. (*)
It's really quite a strange thing to go to bed every night for 39 years being American . . . and then one morning wake up also being British. But, then again, it's been a long road (viz and viz, just for two samples (*)).

I especially like that 'British Citizen' bit there, under my name. I also quite like this. Do not mess with Her Britannic Majesty.
Not my favourite passport photo of all time; but, then, hardly anything compares to this classic of the terrorist genre:

"Five words: Randomly selected for additional screening."