After a beginning of season 5 quite lame - IMO - I think that GA seems to be definitely back on tracks!
The crossover with Private Practice was brilliant. I had the feeling to be experiencing the show I 'fell' for a couple of years ago. The interaction between the characters was great, the medical cases were poignant and some lines were very funny. I still think that it's a shame Addison left Seattle Grace but every time she visits is a great moment. It was nice to have a Denny-free episode and seeing Izzie getting sick was disturbing, weird and sad at the same time. I just wish she would talk to Alex about it.
The whole thing was very good. One drawback though: Sadie's exit reminds me of Hahn's one. Nobody ever noticed until now that she didn't know anything about medicine? That's very weird!
Look forward to the next one, and it's been a while since I haven't been excited at the idea of a fresh episode!