A few things here are impressive.
You have cleverly made the distinction of phones, rather than smartphones, in your assertion that Apple's supply chain isn't impressive in the act of shipping 0.6m iPhone/iPad devices each day for a quarter.
When all unit shipments are considered Nokia actually ships slightly fewer than 1m phones per day (2012 it was approx 340m units shipped) or 0.93m per day.
Apple doesn't manufacture phones, they manufacture smartphones. Same for a huge portion of Samsung's unit shipments. Same for a small portion of Nokia's shipment, but the real grist here is in how much easier it is to make a dumbphone than a smartphone. It's practically prefabbed for you.
Here's a dumbphone teardown: http://www.formymobile.co.uk/3310disassembly.php
Here's an S5 teardown: http://www.ifixit.com/Teardown/Samsung+Galaxy+S+4G+Teardown/...
Manufacturing and assembling a dumbphone is easy, comparatively. Fewer components overall. Nothing fragile or fiddly requiring human QA (wifi). Nothing expensive (gorilla glass, capacitive screen) which hasn't had 20 years of mass-production driving its margins up.
So that's impressive.
Also impressive is shipping different devices in these quantities each year. Apple currently manufactures and sells iPhone 5 (16, 32, 64GB), iPhone 4S (16, 32, 64GB), iPod Touch (16, 32, 64GB), iPad (16, 32, 64, 128GB) and iPad Mini (16, 32, 64GB). Judging by revenue ($180 per iPod sold), a big portion of the 5m iPods sold in the quarter were iPod Touch.
Also impressive, I think, is that every two years, Apple ignores what its supply chain can do and goes back to the same 10-15 people to ask what they can do to improve on an already high quality device. Then they gut the supply chain and build it again from the ground up to make the better device.
They're in a tock rather than tick year for a new iPhone, but that just means that their supply chain managers and fabrication designers are in a tick year, preparing factories for what it will take to build iPhone 6 whilst iPhone 5.1 is still being shipped to 37 million people each quarter.
In brief, the impressiveness here is in the complexity of the devices; the breadth of different devices being manufactured; and the philosophy that leads to innovation not just in design but manufacture.
This is also true of Samsung. They are accomplishing astonishing things with their supply chain and, unlike Nokia, genuinely do ship well over 1m phones a day, of many more varieties than Apple.