A good job

I dont think reflectivity should be turned up on any of it, that would just make it look made of a ceramic material. try to turn the specular down to diffuse the hilight more and give it a plastic feel.

rendering wise, duh...I have to advise you, learn the basics of rendering first before delving into Mental ray. This is a common misconception with alot of new dudes alike. Just cos its MR doesnt mean its going to render you an AWSOME image, Ive lost count of the amount of renders Ive done in standard Maya Software that have left peoples MR renders behind.

I'll have to hurry with my next tute for this site on rendering....

Cheers
Jay