Summary: The 18-250mm’s compact size is likely to give it particular appeal for those who want an easy-to-carry all-purpose lens. However, in the middle of 2008 Tamron brought out an 18-270mm lens with in-built vibration compensation, which is an all-round better zoom (albeit a costlier one).
Tamron AF 18-250mm f/3.5-6.3 Di II LD Aspherical [IF] macro (Nikon) - Review / Lab Test Report
27 September 2008
Conclusion: Early user comments already suggested that new Tamron AF 18-250mm f/3.5-6.3 Di II LD Aspherical [IF] macro does not only offer a longer range but also a higher quality over the old Tamron AF 18-200mm XR and the lab results confirm these impressions.
Excerpt: The star attraction on the Tamron 18-250mm f/3.5-6.3 Di ll LD (IF) Macro is the impressive focal range. The massive 18-250mm range makes this the world's only 13.9x zoom lens (based on Tamron's research into lenses for DSLRs) designed for DSLRs with APS-C sized sensors.