I have had nothing but good experiences with the existing (non-L, non-IS) macro which seems almost impossible to improve on optically, but the addition of IS is a welcome feature. Price is rumored to be around $1,000, or twice that of the non-IS lens. If your macro photography is tripod-based, I would find it hard to see spending twice as much on this lens, as IS is wasted in tripod work. Further, from a definition perspective, I find that making razor sharp 18″ x 24″ prints from my non-IS macro is trivial and see no reason why these would not scale just fine to 30″ x 40″, based on what I am seeing on the screen of my 24″ iMac.

So the new lens may be better on paper, but how much better than my experience can you get? Worth thinking about. Some recent snaps with the non-IS Canon macro (using Helicon Focus) appear here.

DPReview has the scoop.