The Giants winning is a good thing for opportunities in the money line in future Super Bowls. The money line of -400 is too cheap relative to a point spread line of -12, although Jeff Fogle (a guy I respect tremendously) disagrees - see this thread on LVA Sports for a discussion on that issue.
Anyway, if you agree with me that the money line of -400 is too cheap and grabbing that along with +12 on the Giants was a good combination (in appropriate amounts of course), then the Giants winning the game wasn't good (but it wouldn't have been any worse in that combo than the Patriots covering the -12 points if you bet the correct amounts). But to keep things optimistic, it is a good thing for future Super Bowls. The public won big on the money line, the sports books got scared. This means the money line will be that much better of a bet in the future. Gotta look on the bright side.