Stewart's age means he's probably not able to speak with that commanding voice he once had. But the series until now definitely has portrayed Picard being weak, old, uncertain, dominated by others and a shell of his former self. He actually reminds me of the "alternative timeline" Picard that Q engineered in "Tapestry". Weak, lacking confidence and ambition. TNG Picard would never tolerate the sass he's put up with from the likes of Raffi.
Stewart in interviews has seemed 'younger' than how he was playing Picard, I think Stewart was purposly playing him older.