Broken Base: Omnipresent. It was either a cool experiment that isolated the various components of their style, or it was a scattershot mess that strayed too far from their codified sound to the point where it didn't even have a recognizable identity.
Replacement Scrappy: James King. He's long since become an exceptional drummer in his own right, but his style was far more straightforward than John's, and his lack of experience (he had only been playing for two or so years when he joined) meant that he had a great deal of difficulty playing John's material live. Basically, he bit off more than he could chew at the time. He even admitted that he was extremely inexperienced at the time and still had a whole lot to learn about drumming.
Unexpected Character: Kitano Ken makes a surprise appearance as an old man, but he's doing pretty well, apparently he financed the company Origin works at.
The Video Game
Remake Difficulty Spike: This game wasn't easy to begin with, not even 1st quest much less 2nd, but Darkflamewolf somehow managed to greatly raise the difficulty in both quests and add a third quest to top them both.