I'm going to dive right in, and try to be brief. (God, I've been saying that a lot lately. I'm not very good at it).
Meredith is looking for a research project, and although she struggles with it at first, she eventually decides to go with a project her mother had started years before. Her and Christina are still in a bad place, as Meredith is still angry with Christina for not being there for her as she struggles to balance her newborn baby with her career. I liked this plot, because I like to see the growing and adapting Christina and Meredith friendship, and I also like seeing Meredith continue to be passionate about her career.
Christina meanwhile forms a professional connection with Shane, to her surprise. (There's this really uncomfortable scene where Shane basically breaks up with Derek because he decides to work with Christina... that was awkward). Christina also has to deal with Owen and his new girlfriend, who, it turns out, is coming in to observe on a surgery. When Christina tries to talk to her, she learns that Owen hasn't even mentioned that they were once married. This is obviously difficult for Christina. I didn't love this plot, but it was fine. I'm hoping that we can get Christina out of this Owen rut soon and move on to something better. On the other hand, she did some very groundbreaking surgery in this episode, which was cool to see.
That groundbreaking surgery was on a patient who had an inoperable tumor in his heart. He and his wife had decided to spend the last years of their time together just living it up, so when they learn that Christina can save him, they are actually upset. They are in a lot of debt and perhaps even in trouble with the law! Basically, they have both resigned themselves to his death, so life is sounding like a curse now. This was a good example of dark humor done right.
Derek and Callie are working on a brain mapping project, but Callie has lost interest because she was initially doing the project for Arizona. She also wants to focus on finding herself again. Derek too is thinking about stepping back on the project to spend more time with the kids. The patient that they were experimenting on reveals that he was injured in a car crash that he caused by being drunk - two girls died in the crash. When the patient later dies on the table in a brain surgery, Callie says that it was probably a relief to him. Callie and Derek both decide to keep working on the project. Derek tells Meredith that he is going to focus on research and pull back with the surgeries, giving her the opportunity to work while he spends more time with the kids. I liked everything about this plot except for the story with the patient, which felt just a touch overdone to me. Seeing Callie rediscover herself is nice, but I'm still sad that her and Arizona aren't reconciling.
Speaking of Arizona, her plot was probably my least favorite thing about this episode. I did like the acting in it, though. Leah Murphy and Arizona apparently had a drunken make out session, and now Leah is very clingy. Arizona initially tells Leah to back off, to which Leah tearfully replies that she's bad at gauging other people's emotions, and that she understands she goes too far sometimes. I liked seeing this development of Leah's character, and the plot made you feel very sorry for her. In fact, I would have liked this plot just fine if it weren't for the ending, when Arizona succumbs to her loneliness and decides to contact Leah. Ugh, come on. I'm still rooting for Callie and Arizona to get back together, so I hated seeing this.
Webber acts as Jo's teacher and her patient simultaneously as Jo attempts to discover why his shoulder is bothering him. She eventually figures out the diagnosis, and gains Webber's seal of approval as she does so. This was an adorable plot. I liked seeing Webber with that spark of life, and I liked seeing Jo come in to her own as a doctor. I think they have a very interesting student/mentor relationship developing, and I hope to see it explored more.
Now, Alex's plot was a touch cliche, but I still enjoyed it. He has been avoiding Jo, which she is worried about, but it turns out that the reason is justified - he's been going to the bar where his dad plays with his band. One night, he gets to talking with his dad, who doesn't recognize him. After having a few drinks, the two start playing guitar. It was ridiculously endearing to see Alex plunking away on a guitar. I don't know if this actor knows how to play or not, but he did such a good job of imitating someone with only a rudimentary knowledge of the instrument. Alex's dad talks about how he regrets messing things up with his son, but when he shows Alex a picture, Alex realizes that his dad has a new family, and that he's left them too. Furious, Alex tells him that his son would be better off without him. He punches the guy, and leaves. There's this really intense moment where Alex's dad looks up at him in wonder after being punched, like maybe in that moment he finally recognizes his son, but there's no definite way of being sure. I really liked that moment. I didn't like some things, though. The twist with the second family could be seen a mile away. This show already did that with Meredith's dad, for goodness sake. I also think the tension between Jo and Alex is pretty artificial. Why did you get them together just so you could tear them apart by all sorts of problems? Their romance had such a nice build, but now we don't get to enjoy them being a couple at all.
So, this episode was just as good as any other average episode can be. Nothing blew me away, but I had no earth shattering complaints, either. If anything, the episode seemed a bit crowded. There was a lot going on, so much so that a few of these plots didn't have much time to breath. That's something I suppose is often true of this show, but I noticed it particularly in this episode, for whatever reason. Still, Grey's Anatomy keeps the quality very high for a show that's been around so long.