I have only four negatives which I'll get out of the way first:
1. There's pretty obvious gameplay padding to stretch out the game. You could probably cut 2-4 hours of time.
2. May and Cody can be pretty hard to like in certain scenes, which makes it hard to root for them over the course of the game.
3. The book is as annoying as everyone thinks Fi is.
4. I wish the ending was more definitive and less open-ended.

All that being said, I can excuse most of it because this game is just amazing. It's hard to stop a game from getting stale, but every section is so inventive and just plain insane. One moment you're caught in the middle of a war between wasps and squirrels, the next you're solving space puzzles, then you're inside a giant jukebox trying to put on a concert with a glowstick audience and an orchestra you rescued from heaven, and all of these sections invent new rules and puzzles. And through all of it is truly masterful co-op gameplay and beautifully rendered environments and characters. 100% deserving of Game of the Year.

What brings this down is how obviously rushed it is. It recycle's Zero's visuals and combat styles without double-checking the balancing, and how poor the writing was in Yakuza 1 is on full display when juxtaposed with the new additions. There are multiple instances where you are told your next objective before a character actually tells Kiryu where he's going and why. While I admire the faithfulness to the PS2 Yakuza, I would've rather had more tweaks and rewrites to bring it more in line with the rest of the series and that the line between old and new content wouldn't be so defined.