My problem with Poser eyes is usually the iris is too concave which makes it look very bad from an oblique angle... people make them that way so they will have better "catch light" I guess. I think it is better to have good eye geometry and post-work or even use a prop to simulate the catch light! http://en.wikipedia.org/wiki/Catch_light

Also the way the materials and mapping are set up usually the transition from eyewhite to iris is too abrupt... seems to me most people have a dark transluscant transition whaterver eye color they have.

I must admit I use faked eyelid shadows on the eye texture though and usually fake reflections.

The best effect I get is from Dimension3D's free unimesh UVs eye prop used with the textures and bump maps set by Preditron3D which has good eyewhite detail and the choice of fake eyelid shadow and fake or real reflection... I resort to fake reflection most often because I don't want to set up a whole scene facing the figure just for the reflections.