The Tokina 12-24 is a well known lens for APSC format. It performs ok
on cameras up to 14 mpix and on some with higher pixel count. On the 24 mpix
sensor the NEX-7 uses, it is somewhat soft, but it performs well for all-round use

You find no real good sharpness point right away, full open she has a sharper center
and falls off soft on corners and ends. At F11 she performs well, but still
without an exciting sharpness all over. Adjusting focus manually is tricky, but,
once you have the feeling, you find real good sharpness where ever you want it.
Best range is F 5.6 to 8. I will use her for an all around lens, a workhorse for just
anything. Unfortunately, it is big and looks heavy on that small camera

Absolutely a lens to take a real great shot out of the NEX-7. The same
lens with Sony A mount might perform better, but I doubt it. With an appropriate
adapter it will give you more comfort, AF with LA-EA2 adapter.
For all-round shots and tourism she does well, no need to worry for good
shots for the family album an home use.
But, the 18-55 kit lens performs better, faster and is lighter to carry, despite the
Tokina has a better corner sharpness and wider angle.
If you can live without this wide angle, do not buy one, or go for the 11-16 lens.
If you have one,use it occasionally for tourism. It is anyway too heavy to keep
it on the NEX permanently. The new Sony 10-15 will be a better choice,
unfortunately Sony has put the price much too high for it.