Nice deer nice pic!
Because you asked I will give my opinion... I see "young deer" written all over this dude! In my opinion (and you know what opinions are usually worth

) he isn't a day more than 3 1/2 if that. Of course in some areas a 3-3 1/2 year old IS a mature deer [&:]. Small tight skinned face, no well defined wrinkles under the ear, no droop to the belly although as has been mentioned with his head down it is hard to be extra accurate, and I also don't see the bulk that is normally associated with a mature buck. I would be surprised if he netted P&Y after deductions although it would more than likely be close.
It does appear that he has an injury to his left ankle.
All that aside, he is a beauty regardless of his age!