I really enjoyed this episode. I subtracted .5 for Dr. Dixon and for Izzie's monologue about great sex. I loved that George noticed Izzie's losing it, that Alex wants to be a better man, Cristina and Owen's kiss in the boiler room... I wish there was more Mer/Der because I like seeing them together as a happy couple, but I'm just grateful they are together and aren't broken up. And I'd much rather see her with Derek than glued to Cristina, I'm all for close friendships but it was getting annoying and unrealistic. I'd rather see fun romantic relationships and tension amongst the friends at this point, rather than the other way around.
Sadie was more likable in this episode, and I really like her for Callie now. I really love Mark and Lexie, and I can't wait to see further character development there. I assumed from all the hints in the season premiere that they would hook up, but it's happening a bit sooner than I thought it would. I hope it's going the relationship route and not just a standard Grey's fling, because that's kind of old and tired, and these characters are in need of growth and development to keep from being boring plot devices for other characters. I know most people think Grey's is going off the deep end, but I'll wait out the ridiculous Denny storyline before watching reruns of the miserable season 3. I'm looking forward to seeing what happens in the second half of the season!