[JohnFen]

The Newton ended up a commercial failure in the end (although for a while it was successful enough to support a few independent software companies, including one of mine), but a whole ton of the lessons learned from producing it were applied to very successful products following it, such as the iPhone.

I think a reasonable case could be made that the Newton was not a failure in the big picture, in the sense that without it, a couple of Apple's later efforts would not have been as good.