Why would you not pre-order if you could? I mean minus my personal issue with the game's audio, it looks like it will be a pretty decent game with a great storyline. The interactive movie type of thing that I love. In case you are not sold on the visuals and the story, take a gander below all of this for some new screen shots fresh from GDC and a trailer for the above DLC.
Now we only have to wonder how long it will take before the pre-order codes hit eBay and Craigs List for people to make a buck. Never understood the point in selling these exclusive DLC codes myself, but people do it and people buy it.