I must confess I enjoyed very much the collective madness induced by the wedding+valentine combination that is "I do".
This episode marks a turning point in the treatment of sex by Glee. Up to now, sex was considered as a source of slapstick . the various jokes of Brittany's promiscuity) or as something precious and holy (as in the "first times" episode). When here we see all the various couples that enter in the hotel bedrooms happily singing "we've got tonite", you understand that something's changed. Some people could consider it not appropriate for the tone of the show, but surely it exhibits a more laid-back and "adult" view of sex. It's the New York point of view here, not Lima's.
It is still not sure what all these old and new pairings will bring to the general plot of the next episodes. It seems to me that at least the main ones (Rachel+Finn and Kurt+Blaine) were put mainly to show their final destiny; they are endgame, as Finn says. I also liked how the authors managed to convey their different interpretation of the event, especially in the Kurt and Blaine situation. Others, like the Quinntana combination, seemed to be put just to give a treat to the fans. The feeling is that all of them somehow grew a little. In any case it was fun!
Another merit of this episode was to put an end to the awful Tina storyline.
Also, in all this madness, the "normality" of the Jake-Ryder-Marley relationship is a breath of fresh air and it was well played in its clich.
However not everything is fitting well. The episode comes also with its dose of weirdness. First of all, the fact that nobody seemed really upset about the cancellation of the wedding and Emma's escape. Come on New Directions, I know you want just to hook up in the hotel's bedrooms, but show at least some sympathy!
I'm also conflicted about the two big "revelations" concerning the Rachel and Brody couple at the end. surely they will push their New York plot forward, but I wonder if it was really necessary.
I'm also not that crazy about the Artie development.