seems to me that this lens is an improvement over the first version of the kit lens in that there is less purple fringing, less distortion at 18mm, and the build quality is noticeably better. all in all, I think it's a great value for a weather resistant lens.
all pics processed in PSPx2 ultimate w/ "quick fix" - usually added brightness and sharpness.

Camera: Pentax K10D
Exposure: 0.013 sec (1/80)
Aperture: f/8.0
Focal Length: 18 mm
ISO Speed: 100

Exposure: 0.001 sec (1/800)
Aperture: f/5.6
Focal Length: 47.5 mm
ISO Speed: 100

Exposure: 0.017 sec (1/60)
Aperture: f/5.0
Focal Length: 37.5 mm
ISO Speed: 320

Exposure: 0.033 sec (1/30)
Aperture: f/5.0
Focal Length: 18 mm
ISO Speed: 125
Exposure Bias: -0.3 EV