For those who haven't seen the project, designer Edwin Tofslie assembled nearly every Apple product from the company's history into one giant picture. And studying the trends while they're all laid out is like re-watching The Sixth Sense—pretty obvious in retrospect.
My critical analysis: square, circle, square. And though there are a few abnormalities in the line that show even Apple didn't know when the taste tides were changing, like 1996's abnormally curvy Performa, the statement is ultimately quite cohesive. It's like paging through old fashion magazines, but way, way, way geekier (yes, we just used "way" three times in a row). Hit the link for a gigantic version that you can actually appreciate.