Road movies are pretty easy. Whether the people on the journey have just met and are getting to know each other or who don’t like each other and have to overcome animosity, all we ask is two things. First, we want to see some entertaining adventures along the way, some challenges to be overcome with skill and courage to give the characters a chance to get to know and appreciate each other, and to give the audience a chance to know and appreciate them, too. Second, we want to see those moments of realization and appreciation, and we want to feel that they develop naturally, believeably, even in a silly comedy.

This movie fails in both categories. Miserably.

It is painfully phony and even more painfully un-funny. Jokes that don’t work the first time are dragged out interminably and then repeated. And far too many of them involve toilet humor. And the syrupy little lessons about the importance of family values are forced and synthetic. There’s no sense of irony when Bob (Robin Williams) tells his son Carl (Josh Hutcherson) that they should have a “Seventh Heaven” moment to talk about Carl’s feelings about being short. They don’t have any genuine examples of family communcation to draw on.

The movie begins with a sweet scene of Bob putting his little girl to bed and promising to be best friends forever. Tt then cuts to the little girl as a teenager (pop star JoJo as Cassie), treating her father with contempt as they pick up one of her friends on the way to a party for his company.

Bob (Robin Williams) misses the loving daughter he used to have. He feels out of touch with both of his children and his wife Jamie (Cheryl Hines of HBO’s “Curb Your Enthusiasm”). He knows that if they take their planned vacation trip to Hawaii, they will go off in separate directions. So when he is ordered to attend a business meeting in Colorado in the middle of the time scheduled for the trip, he rents an RV and tells the family they are going camping instead, with those fatal parental words, “C’mon! It’ll be fun!”

Incidents along the way designed to let the characters reveal themselves and learn lessons through challenges: bad driving, repeated problems with the seatbelt and repeated failure to remove the blocks keeping the RV from sliding away, raccoons, rain, falling down, and an excruciatingly long scene involving disposal of the “leftover” sewage, which ultimately spurts and explodes all over everything, but especially all over Bob. Funny? No. Revelatory of character or of lessons learned? No, because the characters have no, what was that word again? Character. They are just superficial generics chosen seemingly at random from one of those anyone-can-write-a-script software packages they sell in the back of movie magazines. They have all of the depth and all of the motivation of paper dolls. When, all of a sudden, the script calls for the family to decide they all love each other and nature, the moment would be shockingly abrupt if not so listlessly presented that it almost passes by unnoticed. The business conflict Bob faces is similarly uninspired and un-involving.

There are a couple of funny lines and a bright moment here and there when Williams gets to go off script and improvise. Jeff Daniels and Kristin Chenoweth bring a lot of spirit and humanity to their roles as the relentlessly cheery Gornikes, who keep showing up to get Bob and his family out of trouble and who get nothing but bigoted rudeness in return. But the paper-thin characterizations, snail-like comic timing, and absence of a single genuine feeling or action make this, as the Gorikes might say, not anyone’s cup of sunshine.

Parents should know that the movie has some strong language (two b-words, bathroom terms) and extensive, graphic, and very gross bathroom humor. There is a great deal of comic peril and violence, though no one is hurt. Characters make references to marital sex, prostitution, and teen “making out.” While the movie appears to make fun of characters who are impossibly cheerful, homeschool their children, and like to tell stories about how Jesus saved them from a tornado, a strength of the movie is that the family is portrayed as loving, honest, very close, and intelligent.

Families who see this movie should talk about why Bob did not feel he could tell his family the truth and how they felt when they found out what he was doing. They might also want to talk about the kind of compromises people make to take care of their families and the kind they cannot make without losing their sense of what is important. Why do teenagers like Cassie behave so rudely to their parents? What made the Gornike family so happy?

Families who enjoy this movie will enjoy Lost in America and National Lampoon’s Vacation(both with some mature material) and Lucille Ball and Desi Arnaz in The Long, Long Trailer.