Really Nice Shahank!
I would suggest you to take this to another level.
I dunno if this will help or not but this is what I personally suggest:
A bit of more glow on eyes to make it look more realistic( I think you have a bit there but can't see it).
How about a background with less clutter? Browse around here on CG tantra there are some fantastic potraits done by pros and also consider colour tone with the lighting on the face!
Loved the Z brush work especially wrinkles on the face. In which application have you done hair, is it Photshoped ?
Keep it up!