7.8/10. A tale of two halves. Let's start with the less successful stuff. The drunk train stuff felt discordant with the more serious stuff going on in Robin's half of the story. Showing Barney meeting Quinn and liking her feels like a repeat of the whole Nora thing (which, hey, it may be that the actress who played Nora had to leave the show and so the folks behind the scenes decided to replace her with someone who fills the same role), even if I think this actress has better chemistry with NPH. Throwing in a bunch of Long Island guido stereotypes didn't do much for me either, nor did the Beautiful Mind parody.
But Robin's part of the story was really strong. I think the rewatch turned me around on Kevin. Sure, he's still something of a device, but he has a distinct character, he meshes with the group, and he's very good to Robin despite how repugnant the start of their relationship is. The proposal is rushed, but what comes after, namely Robin's concern that she needs to tell Kevin she's infertile before she can accept his proposal, is strong stuff. I go back and forth on Cobie Smulders as a comedic actress, but she consistently knocks those big dramatic moments on the show out of the part. Her tears, and joy, and subsequent devastation when the proposal goes from something that requires a terrifying confession, to something that carries with it the bliss of acceptance, the dismay of the realization that there's more they need to work through, is a superlative bit on the show.
There's a lot of talk in the episode about owing people for things in relationships, and it ties really nicely between Marshall and Lily's joking bits about pleasing a mother-in-law or other tasks asked of significant others, and the idea that Robin can't "owe" Kevin for the rest of their marriage for taking the possibility of kids away from him. The contrast between the two of them overcoming Robin's fear that her being unable to have kids would scare him away, and then being hurt by the fact that she doesn't want kids, adopted or otherwise, actually driving him away when she presses him on it, is piercing. Agian, strong emotional work from the show that adds depth to Robin's character.
Then, there's the ending, which I'll talk about more in the next episode.