There is some important info here.  If you do not have a seat by assigned number, you are likely in the 'overbooked' category and are at risk for being bumped.  The bad news is that there is significantly less capacity, so the length of delay in flying out to your desired destination could be days. 

The actual data:  "Bumping is still relatively rare, affecting fewer than two passengers out of every 10,000."  Its the rescheduling after you are bumped that is a problem.

For those that are going on a cruise, or meeting a tour -- going a day early is very very highly recommended.  I do that always, even when I drive!

From the Wall Street Journal click http://online.wsj.com/article/SB10001424052970203278404574416813210135226.html?mod=dist_smartbrief