Value is subjective. Unless it turns out to be a shit game it will be, to me, worth $50. Rising was fairly short and seemed a bit rushed to me, and had fewer unlocks other Platinum titles like Bayonetta and The Wonderful 101, but it was still worth full price on release to me and I wound up playing through it like...five or six times, excluding chapter replays. I actually bought it twice; first on PS3 then on PC.
But I love character action games and find them immensely replayable when they're well designed, which Platinum's titles always are. It's like a platformer; I don't just play to the last level and call it quits. I insist on finding all the little collectables, unlock bonus stages, and get good scores because that's where the replay values lies.