very light weight compact lens, i even don't have to buy new bag.
IS really helps, even if you have stable hands, even the wind at 300mm can move you.
image quality: very satisfying, especially by comparing to other brands like sigma or tamron.
i think this lens is really enough for even pro shooting.
any other more expensive is passing to the Luxury (which is really not nesesary).
i gave build "10" because if you'll treat it right, you'll have it in one peace, as any equipment.
if you'll disrespect it, even L lens will break eventually.
i have my "pitty" 350D, with no weather sealing. it passed sand, drops, water, beach etc... and it's still works like a new one.
just like in Pulp Fiction: WINSTON "You hear that, young lady? Respect."