This one gets by on the laughs. Ted taking his class to an ill-fated field trip with stops at his favorite bar among other unlikely locales is a bit of a wacky sitcom premise, but the way it turns into a perfect focus group (replete with a good brick joke in the tag), and dovetails into Barney's "Ewok Line" which combines two of my favorite things on the show: elaborate theories and solid Star Wars reference, manages to save the storyline and make it pretty amusing, even if Barney's dickery about it with Nora hurts an already weak relationship the show is trying to build up between the two of them.
Marshall's story about trying to save the future for his child, and getting his fatalistic boss (Martin Short) to get on board is pretty cheesy in itself, but it's still a nice little heartfelt moment at the end, and the subtle bit that the various employees somewhat resemble Ewoks, with the "yubnub" song going on in the background is good stuff.
But man, the whole Robin and Kevin thing just does not work. The group is right -- a therapist dating his patient is super creepy, and two hours of the therapist venting does not really even that out. It doesn't help that despite the show's attempt at some meetcute-esque business with their daily diner dates, Robin and Kevin don't really have much chemistry to try to justify the creepiness psychologically. It makes the whole thing into a pretty weirdly-aimed story that the show at least acknowledges the weirdness of, even if it tries to handwave it in an unsatisfying way.