If you ask me, the entire Apple approach is a conceptual failure - but obviously a lot of common people have fallen in love with it. It's not very different from a religious following, with all of the inherent implications. But more on that some other time...
But - Apple had also launched a slew of products that were downright business failures. This gem of a piece lays down the goods on ten of them:
1) Apple III
2) Lisa
3) Portable Mac circa 1989
4) The Newton...
5) The Pippin (never heard of it...)
6) The 20th Anniversary Mac
7) Apple eMate
8) The Hockey puck mouse...
9) Powermac G4 Cube
10) The U2 iPod
From Business Insider: From The 'Apple Lisa' To The U2 iPod: Apple Products That Totally Flopped