Hey! If you want to pay a lot of money on the assumption that extra content released for BioShock Infinite will be good before any of that content is even announced as existing or detailed even slightly, 2K are going to offer you that chance! Lucky you! No one can tell you if doing that will be worth it because no one other than people in the development team have seen any of it!
Players will be able to gamble on faith alone that content released for a game we aren’t yet able to prove the subjective merit of will be worth buying. On March 26 they can pay a significant amount of money ($15.99 on Playstation, 1,600 points on XBL) up front and hope they’ll see a return on their investment. Though they’ll receive the content 30% cheaper than had they bought each piece of DLC separately, it ensures that they’re locked in purchasing all of it.
Some of it might be terrible. If even one of the three add-on packs isn’t worth it and you don’t want it you’ve basically spent that money for no reason.
The pass also includes a bunch of meaningless preorder incentives like a skin for guns that turns them into shiny gold magpie trinkets, upgrades for your weapons and character that presumably the game will still be playable without and remain as compelling an experience as otherwise.
Purchasing this is entirely your choice. Do it if you feel like it. Buy it if any of their pitch makes sense to you.