I've never played Corruption, but I've played Prime 1 and 2. And if 3 is similar at all, it will be a little confusing at first. However, with the inclusion of NPCs in Corruption (talking characters to help the story and game along), the game might be a little less daunting. I think you'll enjoy it no matter what. Instead of worrying about what's going on in the Metroid world, watch Gametrailers.com's "Metroid Retrospective" to learn what situation Samus (the main character) is in now.
If your interested in Prime 3 at all, get it. I can almost guarantee you won't be dissapointed.