The best thing about Rescue is that it teaches you to rescue yourself more so than someone else.
A big part of the course is what pir8 posted,but I would like to add that the best thing you can get out of a rescue course is to be aware and have the ability to recognize a potential problem before it happens,thereby preventing a possible rescue of yourself or other diver.I tell students the best rescue diver is the one who never has to do a rescue.