It was a shock in the way it brought existing components together into a complete, well rounded package. Was it perfect? No. But, was there another cell phone like it in world, widely available and easy to use with stable & intuitive software? No.
Many people seem to have forgotten how really cool it was when it was introduced... it was radical; not entirely new, but radical.
The things we take for granted - eg, pinch to zoom, were mesmerizing to watch when the first iPhone debuted; and mind-numbingly simple in retrospect but completely brilliant at the time. The fact that were now take that interaction for granted means we've either been spoiled, the iPhone's been ripped off since it's introduction, or Apple's UI designers really did reinvent the cellphone. How much of each is a factor depends on your point of view. It's a bit of each, tbh.