Terrific Starter Lens - Very Versatile, nice results, great price
Just picked up a Pentax K20D but since entirely new to the Pentax line, I have ZeRo glass to go with it. Since one of the attractive features of Pentax is their dedication to backward compatibility, I wanted a quality lens I'd be willing to keep for a long time but also some major "bang for my buck" in terms of versatility. This was exactly the ticket.

Having used SLR's for over 20 years [starting with the old Maxxum line} I'm used to a solid feel and don't like much of the lightweight plastic junk. This lens has a solid feel without the weight. Comes with a lens hood and cap. Very intuitive design. Works flawlessly with the Pentax K20D...acceptable speed, crisp clean photos. Since the 18-250mm is effectively 27-370mm due to digital, this is the perfect lens to leave on the camera for those impromptu shots.

In comparision, I also purchased the Tamron 90mm with 1:1 Macro - the lens takes some lovely photos but without a doubt, I like this lens better. Quieter, faster focus, more intuitive design, greater substance without the weight. If I were to only select one lens this would be it...since I only have two right now the Tamron is 2nd choice due to it being a nice portrait and 1:1 macro for a competitive price. The Tamron takes some stunning macro shots and makes a nice portrait lens...combined with this Pentax for all around use I'm very pleased with my starter package in both performance and price.

Nice Walk Around Lens
Being new to dSLRs, I decided to purchase this lens for my new K200D. It is a very nice walk around lens and I used it on a recent trip to the Smokies. I was able to take some excellent pictures using just this lens and the zoom telephoto allowed me to take a variety of picts of the same scenery using the same lens.
The only fault is that you have to remember to lock the lens when not in use. (There is a "lock" button on the lens) If you don't, the lens will extend to full length if you point it downward, like when you hang it around your neck or try to put it in a holster case.

Overall, I am extremely satisfied with the lens mounted on my K200D. Then again, since I use my camera for kostly landscape and scenery, and I am a newbee when it comes to dSLRs, take my comments for what they are, as someone very happy with his purchase.

solid zoom
a little pricey for a 3.5-6.3 but a very solid "all purpose" lens. On the wide end there is some obvious distortion near the edges but I like that compared to my other pentax lenses. And, im pretty sure this is one of maybe 2 options in this zoom ratio so there you go...

quality issues?
This lens is said to be a rebadged Tamron. I wouldn't care less. But if quality becomes an issue, that would be a totally different story.
I bought this lens because it now bears the Pentax name, and it's a really cool carry-around lens. Of course I would expect it to be of the same high quality as other Pentax lens would have.
Other than the VIGNETTING effect, the first thing I noticed was when I am checking image on the LCD at the back of the camera, while this lens is pointing downwards, the lens will SLIDE OUT to its full lenghth. The same thing happens when I am taking the camera from the camera bag.
Just like taking the small blue pill before you go to an important business meeting.
Is it because the front end of the lens is too heavy? I hope this is just a small problem that no one else would have. In any ways, I am probably going to return it.

Dust catcher
I sent my first 18-250 back to Amazon for replacement due to dust behind the front lens element. They promptly sent me another, and it was fine for a few months, but now it has dust specks in the same place. The lens has never been used or stored in a dusty environment. Its maximum aperture makes it a slow lens for low light use, so any dust is reducing the amount of needed light.

It is a very sharp lens with minimal chromatic abberation, but it does have a pincushion problem that can be managed with good photo editing software.

Zoom creep is another problem, and it is so loose that I'm supposing the dust is entering there.

The lens could be a joy to use, but the price is very steep for the for the quality.