I thought in the short segments he was in, he seemed intelligent, strong, humble, etc.
Maybe that is the big surprise! Cersei, Daenerys, and Jon Snow get caught in an epic battle and end up killing each other, as humble Gendry strolls into the ruins of Kings Landing and it's revealed to everyone that where the entire story started, is the same place it's going to end. The reason why multiple "hands of the kings" died is the revelation of this young man.
I like the twist of Arya being Queen though. King Gendry and Queen Arya Baratheon... also it circles back to season 1 and Robert B. telling Ned that they were going to join houses and have their children wed!!! It all happened, in an odd sort of way...