If you don't have plans to see this movie, you can check the spoilers here and then come back.
It's not easy to come up with a clever take on the worn out genre that is the romantic comedy, but I proclaim this movie a success in that regard. Writer/director/star Michael Showalter's premise of following the jilted "other guy" from every other romcom who gets shoved aside so the destined lovers can get together in the end is a unique one with plenty of material to mine. Showalter's goofy charm is perfect to propel an off-center protagonist like Elliott Sherman and he does a good job balancing the quirky sense of comedy he and his "State" buddies generally bring to their work with a full-on send-up of what you'd expect from typical movies of this fare, tongue firmly in-cheek and overselling the dramatic moments hilariously. Fantastic supporting cast as well, particularly Justin Theroux who does brilliant over-the-top parody work as the "right guy," milking his character's oversensitive monologues and breathless admissions of love. You can see Elizabeth Banks beginning to come into her own as the amazing comedic actress she is today here, not quite fully as developed as she'd soon become, but showing signs of greatness in her more manic scenes. Michelle Williams isn't out-and-out hilarious, but she's cute, which is really all that's asked of her. Great cameo work by Peter Dinklage, Michael Ian Black, Paul Rudd, and David Wain, who gets perhaps the funniest scene in the whole film, fill things out. My issues with "The Baxter" would be that it could maybe stand to lose at least 20 minutes or so, as the plot meanders in the middle somewhat, killing time to get us to a destination we've already caught a glimpse of. Also, as funny as most of the movie is, there are times where Showalter and company botch the transition between touching and absurd, which can be a bit awkward. Mostly a solidly entertaining romp with lots of heart and more humor though; I'd recommend it.