I just checked your last work before this in here, and it was from around 2006, wow. This is definitely a huge overhaul from your previous attempt.
I also checked your portfolio site. Even though it’s outdated, you were already a pro since 2003 or something, phew! You’ve got a lot of experience under your belt. And I started 3D in the December 2012, lol…
Anyway, a little criticism. His eyes are looking great from a shading standpoint (a proper convexity and glossiness on the cornea and concavity on the iris, and good refraction), but the iris itself could be more defined. Here’s a good technique to give more definiton for the iris: http://jhill.xyz/eye-tutorial/
Two good examples I found of his eyes:
http://vignette2.wikia.nocookie.net/marvelcinematicuniverse/images/a/a7/Ben_Kingsley.jpg/revision/latest?cb=20130425205425
http://media.salon.com/2013/10/ben_kingsley.jpg
Notice how the color changes between the pupil and outer edge of the iris. Maybe you don’t need to get the exact look, but something similar to give him even more likeness.