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I've owned the DA*16-50, DA 12-24 and currently own the DA 15, and now own the Tokina 12-24 and Tamron 17-50 2.8 in Nikon mount. My DA 16-45 compares well to all of them.
Compared to:
DA* 16-50 2.8: DA 16-50 was sharper at f/4, same by f/5.6, having the 2.8 was nice. 16-45 is smaller/lighter.
DA 15ltd: 15 is sharper wide-open, better flare control, much smaller and better built. The 16-45 has the versatility that comes with a zoom.
Tamron 17-50 2.8: f/2.8 is fully usable and nice to have, about equal sharpness after f/5.6, with the Tamron sharper at f/4. My 16-45 + K20D brings better colors than the D90 + 17-50, but a touch of PP evens things out.
Tokina/Pentax 12-24 f4: The best all-around WA zoom, IMO. Bigger/heavier than the 16-46, and more of a WA specialist.
Here are some shots from the 16-45: