I appreciate its quite a bit cheaper but does this lens do anything the 70-200 2.8 ii IS can't do?
If you go by current mainstream: NO
Reach, flexibility, stabilization, optical quality and the "look I'm carrying professional gear"factor are all in favor of the zoom.
If you are a little more square than others: YES
lighter, smaller and black. Less attractive to thieves, more difficult to spot, less suspicious in the eyes of officials when entering a music or sport event. When being used on cameras without build in/added secondary grip the lens feels more balanced than the zoom.
Optical quality is inferior to the more modern range of white lenses, however it fits the resolutionof my outdated camera sensors.
Ironic brackets on " Last but not least, being knocked arse over heels by waves, having become airborne when Chinese stage coaches went through potholes big enough to bury the driver in, generates the sudden question if you use your left arm to protect the canon gear in your right arm or your body. Being smacked to ground with a lightweight 900 Euro lens in my hands felt always less painful in many ways than doing the same stunt with a double weight, triple priced lens. " Ironic brackets off