This is an AWESOME piece of glass, I use a Canon 5D mkIII and the combination is breathtaking. My photography is mainly railway related and I have been simply blown away by the results. I use it hand held and even down to a 15th of a second it is pin sharp, the IS is just so good.
It is expensive no getting away from that but in my humble amatuer opinion it is WELL worth the money and you will NOT be disappointed.
Go on treat yourself, you know you want to!!!! ;-)