I got all S' on Son of Sparda, and unlocked the accomplishment (since I'm on PS3) "A Stunning Feat". I have to say, considering this game's more difficult than DMC3, it's actually much easier to get S' on most missions. Sure, a Double S on some of the earlier missions in DMC3 is cake, but it can get much harder to be stylish on Fallen One's and Arkham. However, in DMC4, the entire game's about the same difficulty, whereas in DMC3, it's a ramp, starting out jokingly easy but becoming quite challenging by Mission 19.