I am very impressed with the way Corruption is turning out. The new control scheme will have the game feeling completely new, and at the same time have FPS lovers all over it. With Prime we got pure Metroid in 3D, it made us happy. With Fusion the franchise was advanced forward a bit, giving us the same gameplay we have loved for years, pluss adding alot of story to drive the game forward. Then with Echoes, we were steadily given a tiny bit more story and cut scenes, along with our first bit of voice acted dialogue. Now with Corruption, Samas has allies that aren't dead(yet) are willing to fight with her, there is voice acting, and the cut scenes are alot more flashy so far than anything we've seen in the last 2 3D console titles.
I imagine Nintendo or Retro has wanted to flesh out and develop the Metroid universe since the franchise came back in full force last generation. And instead of throwing it at us all at once we were gradually getting it piece by piece. Well Fusion really threw alot at us story wise, but still. Oh and Hunters also had an amazing opening. What ever, im saying it was all bound ot happen, Metroid wasn't going to stay silent for ever. And im sure most of the game will have Samus all alone somewhere in some deep dark cavern.