(USA) No, it is not as brilliant as “The Hangover.”

But let’s face it, it’s unfair to expect “Due Date” to top director Todd Phillips’ 2009 ballsy male-bonding road trip film, which set a new box office record for an R-rated comedy and is arguably the most hilarious flick of last year (and if you didn’t like it, by the way, stop reading this and go get a shrink). So with this in mind, Phillips’ new road comedy starring Robert Downey Jr. and Zach Galifianakis, is fairly entertaining. But given the fact that the go-all-the-way hilarity from “The Hangover” is rather half-baked here, and the little Phillips seems to have learned from the chemistry and wisdom that dazzled in John Hughes’ “Planes, Trains and Automobiles” (despite the amazing similarities between it and “Due Date”), “entertaining” is about the best word that can be used to describe this film.

The series of shenanigans starts in Atlanta, Georgia, where uptight and snobby architect Peter Highman (Downey Jr.) needs to catch a flight back to Los Angeles to witness his wife (Michelle Monaghan) give birth to their first child. At the airport, he meets the eccentric Ethan Tremblay (Galifianakis, or as we usually refer to him, “the bearded Zach guy”), who’s heading to Hollywood in hopes of starting an acting career, or at least making a guest appearance on his favorite show, “Two and a Half Men.” After several unpleasant incidents, Peter finds himself tossed off the flight with his name on the no-fly list, along with Ethan’s. With his wallet in his bag and his bag on the plane, Peter has no other choice but to drive with Ethan to South California fast enough to make it back by the baby’s due date.

Ethan, meanwhile, is a wannabe actor who carries a French bulldog and his recently diseased father’s ashes around everywhere. He claims to be 23 years old though he’s actually approaching 40. He has narcoleptic fits while driving, masturbates at inappropriate times and arbitrarily changes the route just to get his “glaucoma meds.” Naturally, Ethan’s and Peter’s oil-and-water personalities quickly lead to farce, which runs the gamut from car accidents and hospitals to Mexican border guards.

The tight and intense script has its share of hysterical gags, but at times they are a little fake and desperate, making “The Hangover” look like a real story by comparison. Interestingly, toning down the outrageousness and replacing it with a small dose of sentiment, Phillips explores the issue of fatherhood through the two lead characters: one a father-to-be who grew up fatherless; the other a grieving son who reminisces about the close relationship he had with his dad. Downey and Galifianakis, both in fine form, deliver a strong joint performance as the odd couple. However, unlike Steve Martin and John Candy in “Planes, Trains and Automobiles,” Downey’s remote and bossy snob and Galifianakis’ warm but mega-annoying pothead hardly transcend their personas to become more memorable. Cameos by Juliette Lewis as a drug dealer (seriously, this lady HAS TO stop playing white trash) and Jamie Foxx as the wife’s ex-boyfriend both add to the comic moments, if not that impressively. Bottom line is that “Due Date” is a “Fear and Loathing” story on very weak drugs, but it may be just enough to get us through the days ‘til “The Hangover 2” opens next year.