The 100 is as sharp as any of the other Canon primes. It's too bad they couldn't have made it an f1.8 or f2 (but then it wouldn't be able to be a macro)
my 100mm macro is one of my favorite lenses, its sharper than any of my other lenses, including an L, and its fun to shoot something different. You'll definitley want to shoot with a tripod, its a must when you get that close to a subject because any little movement screws your photo up, Definitley invest in a good tripod if you don't already have one, i use a bogen manfrotto 3021pro and it is super sturdy and easy to adjust quickly.
as you shoot more and more macro you'll probably want to get a remote shutter release and shoot use the mirror lock function to get tack sharp shots.
I have the 3001N with a 3030 head. Already have the rempote release; thanks for the reminder about mirror lockup . . . I totally forgot about that capability . . . .
rich, those things look amazing, but i just can't get myself to spend the money on one, too expesive, but hopefully when i get the 430ex it will at least get me some good lighting for maro. i hope.