Being released with the 7D, I have a hunch this 100L is mainly targetted at APS-C as it would give them a focal length of 160mm. HIS would be more useful. Having said that, it also look appealing for someone like me whom has been wanting to get a 85f1.8 and 135L. Maybe I'll settle on this lens instead. It is like a 3-in-1.
What I am waiting for is to verify that macro lens have been calibrated for macro work/close focusing. How good will the 100L be for portrait or street photography.
The larger 67mm front element, compared to 58mm will mean that it will gather more light/less vignette for FF.
The 9 blade aperture improvement over the 8 blade shows maybe an even nicer bokeh
15 elements in 12 groups shows a overhaul of the lens arrangement over the older 12 elements in 8 group. Note that despite of having more lens element, bigger barrel diameter, metal construction with seal, HIS electronics, etc. The 100L weighs only 25g more than the 100macro. Thinner glass or lighter plastics used??? More glass elements = more complex light manipulation??? (I am just speculating on this one). The 135L uses 10elements in 8 groups.
So this 100L does give mixed signal about its identity.