When the GOP brags about winning the run-off in Georgia, it's worth remembering that through early October, most mainstream political analysts (with the notable exceptions of brownsox and Swing State Project) thought Saxby Chambliss had his re-election campaign locked up.
Take, for example, Stu Rothenberg on September 14 or Charlie Cook on October 2. Both said that Georgia was a safe Republican senate seat:
So when the GOP crows about their 'big victory,' they should keep in mind that they won where they were supposed to win, and that the flip-side of denying Democrats a 60-vote majority is that with Georgia in the bag, Republicans now hold just 41 seats.