It was clever that they used the reference point of a passport. I don't think I've ever heard of anyone complain about passports being unwieldy.
You hold your passport a few times a year, for maybe a few minutes. Probably less than 1 hour total per year. Many people will 5x that usage-time in just a day.
Passport is also thinner than a pencil, not rigid, and will fold a little around your thigh in a tight pocket.
It will save people a lot of time because they don't have to go to the Apple store, they can use their own passport to discover that the phone is still too big in a different dimension to use with one hand.
Just like the iPod's "deck of cards".
you don't carry your passport in your pocket every day
They are so unwieldy that the US has a passport card because the passport is too big for frequent travellers. I also will complain about how my passport's ID page is the second, not the first page, so you open the passport, and then always have to flip to the second page (unless you use a tiny bit of tape).
Personally I find passports slightly too large to comfortably fit in my pants pocket, and a passport is definitely thinner than this phone. Whenever I travel and have to have my passport in my pants pocket I’m always a bit uncomfortable about it, I usually prefer to keep it in my backpack or somewhere else. If you’re carrying this in a purse then it sounds great. The passport aspect ratio is pretty awesome on phones, I tried one shaped like this at a Chinese phone store last year and enjoyed it. But shoving a $2000 device the size of a thick passport into my pocket on a daily basis feels like a bad idea.