Americans should avoid any economic Schadenfreude. Yes, cheap oil has meant cheap gas, easing strains on households while giving a boost to SUV sales for American carmakers, but falling prices could mean oil companies abandon exploration and cut back on production, which will mean loss of jobs and could lead to deflation.
Deflation can lead to the U.S. having difficulty repaying depts. Also, low oil prices tend to cause debt defaults that, if they become widespread, could affect bank deposits and international trade.