Tamron keeps on surprising DSLR users with its ultra-zoom lenses with performance levels that once was never though to be possible. Tamron 18-250mm f3.5-6.3 since its first introduction has become one of the most versatile lens (13.8x zoom)for APS-C DSLR cameras while offering image quality that is competing with zoom lenses with less magnification ratios. Surely it has some drawbacks like being slow on the long side, chromatic aberrations in certain situations, etc. but overall I think it is a perfect all-round lens.
Now Tamron takes the ultra-zoom DSLR lenses to next level with the new AF 18-270mm F/3.5-6.3 Di II VC LD Aspherical (IF) Macro, taking the world record once again with the 15X zoom, and adding its Vibration Compensation system (VC) in to the game, making it even more attractive for Canon and Nikon users whose bodies lack sensor based Image stabilization.