I have used this lens for about a month - it came as the kit lens with the K10D. I have been very satisfied with many of the pictures from this lens, including landscapes and portraits.
Recommend this product?
At optimum aperture (about f8) this lens can produce very sharp pictures with faithful colour reproduction up to the telephoto limit. The limitations of this lens become obvious at extreme wide angle in strong light where flare can be a major problem. Mid-range to telephoto will avoid the worst of the flare. At the right price this lens is well worth considering - it becomes excellent value for money. This lens is designed as a cheap kit lens and cannot be compared with the DA 16-45mm which is of course much more expensive. If you shoot landscapes at wide angle in strong light, then I would recommend spending the extra for the 16-45mm. Not only will you avoid the worst of the flare but the extra 2mm makes a big difference. If this is not an issue, then for general picture taking the 18-55mm will do a very good job.