The code also works with multiple different orders, so you are not limited to 1 order only. I've used it on 2 different orders and it worked fine. I believe they stated that the order minimum has to be $40 to use the $20 off code but I've ordered a game that was $39.97 and the code worked fine.
Yea, was thinking about getting Medal of Honor pre order......but I don't really want ANOTHER download service software. I kind of like my stuff all in Steam.