1: Geekyness
2: Convenience
3: Price
I called up the nearest Kmart and they said they were going to get 8-15 3DS units in. Needless to say they weren't doing pre-orders, and they were opening at 9 in the morning. That left a huge margin for error for when i'd need to show up to guarantee getting one, and better yet guaranteeing getting one of the right color.
So then i did a couple more searches online, and found that some Gamestops were doing midnight releases. There's exactly one of those Gamestops within a dozen miles, the one at Bella Terra (where i went for the midnight release of FF13.) So i tried calling them up and found that not only had not all the units been pre-ordered yet, but if i pre-ordered now i could even pick what color i wanted!
So given the choice between ordering from Amazon and saving $25 but not getting to wait in line, going to Kmart and saving $25 but possibly having to wait in line for eight or nine hours, or hanging out at Gamestop for a couple hours for their midnight release tonight but not saving any money, i went with the last option.
Of course it would have been a little more convenient if i'd done that research and made the decision before we went to the same mall to see Sucker Punch earlier today :)
Now i just need to finish figuring out what (if any) of the release games i want to get.