There is much discussion about the black dots, without a great deal of experience. I have a 5D Mark II. I can easily reproduce the effect. BUT, in order of image qualtiy impact:
1. Dust
2. CA
3. Sharpening effects
4. Noise effects
5. Black dots
6. Hot pixels.
The problem is noticable at 300% magnification and most people can't even see it at 100% magnification. It is a very minor problem which I have not seen at 100 ISO. It is only marginally more annoying that hot pixels because it is harder to find.
I suppose if you wouldn't buy a DSLR because it can get dust spots you might not want to buy a 5D Mark II because you get black dots under very specific conditions, but really - there are far more important things to worry about in the image than the black dots.
In reply to: "Black spots afflict Canon's new SLR"
December 9, 2008