<<<SPOILER ALERT>>>...BUT then the girl told me that i have to wait 200 years to open the vault...WTF !
Highlight from here---> The "Vault" isn't really a huge supply of weapons and $$$. It is a tomb, built by the Eridians to keep the Destroyer from wiping out the universe. The Guardians that you fight toward the end of the game were created by the Eridians as protectors of the Vault.
The "Guardian Angel" voice who talks to you throughout the game, and encourages you to seek out the vault, is nothing more than a satellite transmission from the Hyperion Corporation. They are telling you this so you will attempt to go there in the hopes of great wealth, and you can defeat the Destroyer when the Vault opens. If not, it would come out, and kill everything. So, when you kill it and think you are going to find riches and weapons, you really only saved the universe for another 200 years. <---to here.
<<<END SPOILER ALERT>>>
I was sort of bummed with the ending as well, though. I mean, you get some $$$, sure, but other than that, you get nothing. No weapon, no shield, no upgrades. I mean, if you played through the game once, and didn't plan on attempting Playthrough 2, you would feel REALLY stiffed by the whole thing. I'm hoping maybe the 4th DLC that is coming will maybe clear up some of the odd loose-ends, and maybe explain the story and whatnot a little better.