Conclusion: I borrowed this from an acquaintance to use while my 70-200/2.8L is being repaired. I'm not making this a direct comparison, since that would be like comparing splendid apples to rotten oranges. This lens has the worst rating of any Canon lens tested by Photodo. I could have told you this after looking at my soccers shots. Simply terrible. I've used Nikon's 70-300/4-5.6G, which has a lower MSRP of $179.99, and that's much sharper.
Pros: lightweight, fast focus
Cons: total lack of sharpness, unsurprisingly cheap build quality, MF ring too small/in a weird place