As a gameplay freaque, I think my narrative interest in Yozora is overshadowed by how he's probably the best boss ever created for a Kingdom Hearts game. The way he moves is cool, the style and flair of his attacks is cool, his quotes are hilariously nonchalant, and his strength is communicated extremely well by the team-- Yozora is a top level video game protagonist who's throwing all of his shiny cool moves at you, and if you don't pay attention and learn, he's going to rightfully stomp on you.
In the scenes, he's just alright. He isn't too much of anything, and for now, I'm fine with it. It was ballsy to let him say the quote from KH1, the first line of dialogue from the entire franchise, but at the very least it establishes that Yozora is important and has been through as much as Sora.
In terms of foreshadowing and mechanics, our secret bosses have gotten better and better. Enigmatic Man was okay, Lingering Will was awesome, and Yozora is incredible.