The A-story, about Ted and Barney deciding to adopt a baby together, had a novel premise and some good laughs in it. It goes off into crazy town when Barney shows up with a baby, but the the reveal that it's James's and he was coming over for Thanksgiving was kind of nice, even the actual cause and effect of all this doesn't really make sense. James's comment at the end that raising your child with a loving partner is worth waiting for is on-the-nose, but pleasant. So this whole storyline is a little off, but entertaining/affecting enough to get a mild pass.
The Marshall/Lily/Robin business about the couple moving out to Long Island and Robin throwing a fit was less successful. Marshall and Lily's apartment being physically smaller when they came back was a cute way to depict the idea of how much tinier a NY apartment feels after you've been away for a while, but the whole bit felt like a retread of what they'd already done with the house. And there's thought behind Robin digging her heels in, but the execution of it is, yet again, pretty broad without much of an anchor in reality or humanity.
Then, of course, there's the reveal at the end of the episode, which I'll talk more about in the next episode, but suffice it to say, it still strikes me as a manipulative kind of teaser and dramatic cliche that I don't really care for here, even if there's some merit in where they go with it.