I have the DA18-250mm. It is a fantastic utility zoom. Having said that buyers need to keep of a couple things about it in mind.
+ It stops down fairly quickly from F/3.5 to F/5.6 at ~70mm.
+ You will get some subtle vignetting at the wide end.
+ You will get some barrel distortion. I have only noticed it on close-up shots but it is worthy to note that it is there.
+ Yes, both the Tamron and Pentax versions suffer zoom creep (like a well used trombone).
But even with those shortcomings, it is a great lens and capable of taking great shots.
A couple of my favorites from this lens...
1/125s, f/5.6, ISO 100 @ 155mm
1/180s, f/6.3, ISO140 @ 250mm