Overall, a very good season. Newer characters incorporated nicely into the plots, some unexpected twists and turns. Nice to see so many of the long time characters evolving more, growing up and into their on air personalities.
Really didn't care too much for the 'singing' episode. Loved how Alex, while still being a difficult person to pigeon hole, was given so many more chances to shine, and show what makes him an excellent doctor.
Best, and most intriguing, relationship on the show, since episode one, has been Meredith and Christina, aka 'the twisted sisters' [per Dr. Owen Hunt]. Another strong season.