I just got the Tamron 70-300 (Nikon version), based partly on your mini-review. I wanted to move up from the Nikon 55-200. I haven't had much chance to play with it yet, but it's leaps and bounds better than the 55-200 (which, to be fair, I paid less than $100 for refurbished). I did remove a little CA on this photo, but it's wide open at 270mm.
DSC_3422 by
awhenUO, on Flickr