Bojan, try this site, Tony Hallas recommends it and it has some good data to help choose a lens before purchasing.
http://www.photozone.de/nikon_ff/755-tokina3004fx
It seems to show very good centre resolution at f/4 but improves to almost excellent stopped down to f/5.6 with the borders and extreme edges improving slightly. It does seem to suffer from CA which oddly, seems to worsen as you stop the lens down with 1.6 pixel width at f/4. No doubt the f/2.8 version would give you more room to move and enable you to shoot at lower f stops.
Hope that helps in some way.