mm, the yellows could use a wash (as far as I can telle from the pics). I think a devlan mud or ogryn flesh wash would do it (the brownisch washes)That would bring the detail back into it.
The metal can benefit from a badab black wash. That would make the detauil pop a bit more. Also the yellow on the claw is a bit to much. Maybe put yellow on the motorpart of the claw (a nice flat plate up top or something) and have the claw metalic. Would look better
IMHO.
Final comment is drill the barrels out of those orks. That will add to the orks, really......
The skin and teeth do work for me, so that is half the model looking fine

. Oh and if you want to know How I do mine (yes another shameless way of showing my own stuff off) check my orks (follow link in sig) so you can see what washes can do...