I too am considering this lens. I am finding most of the criticism read so far to be puzzling. I have read the lens is a poor performer in low light. At f/4.5-5.6 who ever said it should be good in poor light? I've seen it compared to the 300 f/2.8. Hardly apples to apples as the cost comparison should reveal. It clearly beat out the 75-300 in all photo comparisons and since it costs 2x as much it very well should. Flare and halo under certain lighting conditions are the 2 most legitimate concerns IMO. Careful planning should be able to avoid those conditions. Lastly no lens is perfect and no lens does it all. So it seems to me that the pros of compactness, travel capabilities, fast AF, all around general purpose walk around lens capabilities with IS outweigh the cons I have read. Interestingly many of the negatives are coming from people who admittedly do not own the lens. But owners seem to be pleased in general. If there are so many negatives and owners than there should be plenty of these for sale. But I have not been able to find more than 2 listings and both were for more than 35% of retail value. I would say buy it. I might do the same if the right deal presented itself.