Tamron 18-270 vs Nikon 70-300 VR vs Nikon 18-200 – In this DPReview post, "cubsfan61" comments on the Tamron AF 18-270mm f/3.5-6.3 Di II VC LD Aspherical IF Macro Zoom Lens (Nikon mount) compared with the Nikon 70-300mm f/4.5-5.6G ED-IF AF-S VR Zoom Nikkor lens and Nikon 18-200mm f/3.5-5.6 G ED-IF AF-S VR DX Zoom-Nikkor Lens:
It's not quite as sharp as the Nikon 70-300vr, but I think it's a bit sharper than the Nikon 18-200 (I've owned both). All in all it's a great all-in-one with a fantastic range.