Technically it was meant to be Metal Gear Solid, hence it's original project spiel of "Lightning Bolt Action, Metal Gear Solid: Rising". Not until after KojiPro foolishly felt it would be better to change it did it become "Metal Gear Rising: Revengeance".
I think it's the fact that it both draws on Raiden's previous character development, and then completely sh!ts on it halfway through the game. I like MGR and its depiction of Raiden, but honestly, the game went to great lengths to sorta mess up Raiden's happy ending, and it felt like there were a lot of unresolved issues, especially with Raiden embracing his psychotic side, and most of the rest of the game trying to convince Raiden that it's okay to slaughter people like some audio version of Everybody Poops. It's like it tried to be Spec Ops: The Line, but missed the mark and ended up ruining a resolved character.
Jack the Ripper is back, and it's like...great! That's something you wanna bring home to Rose and Jack.