This statement suffers from either viewing the past through rose-tinted glasses or from total cultural relativism in the most pejorative sense.
I'm not sure about 2003, but around 2009, I owned a Nokia N900, which was arguably the flagship Nokia phone at the time. I can confidently state that current iPhones are _way_ better than that phone. On paper, the N900 phone was amazing: it had GPS, Wi-Fi, multitasking, a camera, a touchscreen, and (!) a hardware keyboard, and more. It had a desktop-class browser, on paper. But nothing quite worked well. It was far too bloated for the hardware capabilities of the time. When you came home, it never damn switched properly to WiFi, or it took forever. The same applies to switching off WiFi and switching to cellular when you leave home. The GPS always took minutes to establish a location and easily lost connection due to small obstructions. I recall that I compared it to a friend's iPhone at the time; the N900's GPS was embarrassingly bad and slow.
I can confidently say that today's flagship iPhones (or even Androids) are significantly better quality than the N900, in every way possible.