Quote Originally Posted by wickerprints
The 100/2.8L macro IS, in my view, is geared toward people who are beginning with macro and are willing/able to spend the extra $400 over the non-IS version to get every bit of help they can--like me! And I think Canon knew this, because they did not discontinue the older model. The new model is a tech showcase lens--designed to show off their lens R&D and gauge its future applicability toward the broader EF range.

Nice summary.