My thoughts on...
Triangle A (Terri/Will/Emma)
I really hope this isn't the end of Will/Terri. She's trying to be better, and he didn't say never! He said he didn't know... Of course, then he kissed Emma. Oh, Emma. I had moments where my fondness of Emma almost returned. When she confronted the other judges, I was like, nice. Good. And when she rejected Will at her wedding because he had just left his wife, I had respect for that, too; the notion that she had too much respect for herself than to accept a guy who just had his heart broken. She is a councelor. But then she went and kissed him. I really hope this ends soon and Will/Terri makes their return (I have high hopes in this regard). I continue to ship Will/Terri. Shuesters, Unite!
Kiss, btw? Did nothing for me. If it was supposed to be this great moment, it fell really flat.
Triangle B (Rachel/Finn/Quinn/Puck)
Finn being the leader was love. Finn and Puck breaking up seems sadder than Finn/Quinn, and while it seemed like they were being unduly mean towards Rachel, it seemed deserved when she basically spilled the news as soon as she had it (and was she even sure? basing it on her mind-reading abilities??). That said, when she willing accepted Mercedes singing the ballad, I thought that signaled personal growth on her part. So yay!
Also, I loved Finn's mentioning that he used the copy machine... OH ACT OF DEFIANCE.
Mercedes: I was glad that Mercedes challenged Rachel for the ballad, mostly because while I readily acknowledge that Rachel is a lovely singer (I judge this off the fact that, if indeed she were to play Elphaba in a movie production, I would be okay with it... not as happy as if a young Idina could come through a time machine and do the part herself, but life is full of compromises) I think that Mercedes is just as good a singer. Glee's Imagine cover really cemented that for me (though a final decision would have to be made hearing them both sans autotune).
Santana/Brittany: Santana loves glee and Santana/Brittany is my new hilarious, secret otp.
Performances: Neither of the ballads blew me away, but I did like the can't always get what you wantness (and their choreography on the fly).
I hear that Idina is in talks to be on Glee for many episodes. To which I said, OMG. YES. PLEASE.