Not really. That first video in the replies above is included in the game, so you get the key back-story teed up for you but it's not vital to this game. All you'll miss is that bit of familiarity with the returning NPCs and maybe miss a few references and in-jokes to previous events, but nothing you couldn't happily play without! (Without going into spoiler territory, there's also an origins/history theme to the story which pre-dates the original anyway!).