EF 70-200mm f/4L IS USM.Super sharp.
4 stop IS.
Built like a tank.
Other great stuff.
In other words: This is an UBERLENS.
Why not the 2.8? Too heavy. The f/4 is half the weight.
I like the 2.8, but I don't like the camera strap cutting through my spinal cord.
Seriously I like the snappiness of this lens and it is easily hand-holdable for all day.
Take this traveling, use it for weddings, for portraiture... etc.
Me like it.