This lens does not what the advertisement believes you to.
IS is great if it would really make a difference, i can't tell the difference between switched on or off. This lens is not as sharp as the 24-70 L, not even stopped down, and the use of the I.S.
I told Canon about this and they said: "we don't produce unsharp lenses". Also making a bad production, and make the customer wait for at least 3 weeks to get a new lens is not very proffesional thinking. I cannot afford a lot of lenses, as a starting photographer. (meaning the business, not the pics).
Bottomline, it is a great lens to use, fast AF, nice weight, but for the sharpness or the I.S., better save your money.
I get a new lens next week, but i will sell it right away.