(CNN) -- Watch out! Lock up your loved ones! Another bloated, over-produced, high-concept monstrosity has escaped from the labs at Dreamworks Animation, and it's out to devour your kids.





Susan, aka "Ginormica," has to save the world in "Monsters vs. Aliens."





But don't be too alarmed. "Monsters vs. Aliens" is relatively harmless -- a toothless satire with a knee-jerk feminist theme and a sorry excuse for a plot.





That sounds harsh, I know. Who doesn't want to see a 50-foot woman careening through San Francisco on skates that turn out to be automobiles -- the ultimate demolition roller derby?





But think about that, just for a second. Roller skates work because they have fixed wheels. Try it with motorcars and you won't get very far.





Is that too picky? Perhaps, but you wouldn't find Pixar playing so fast and loose with the laws of physics, and that kind of inattention to detail is typical of the lackadaisical storytelling here and in other Dreamworks animated features. (The talent pool for this one includes the directors of "Shrek 2" and "Shark Tale" and the writers of "Kung Fu Panda" and "The Rocker," incidentally.) High concepts, top-notch voice talent and scattershot pop cultural references are no compensation for a coherent script.





The XXXL lady in question -- dubbed "Ginormica" by her U.S. military guards -- starts out plain and petite Susan Murphy (voiced by Reese Witherspoon), until a meteorite hits her just minutes before she's supposed to tie the knot with unctuous chauvinist Derek (Paul Rudd).





Her rapid growth spurt saves her from that particular fate worse than death, even if at first glance her new roommates don't look like much of an improvement.





There's Dr. Cockroach (Hugh Laurie), a mad scientist who semi-advertently mutated with a bug; B.O.B. (Seth Rogen) an amorphous blue jelly-like blob who gets on just fine without a brain; Missing Link (Will Arnett), a gung-ho amphibian who's all mouth; and a giant dust mite called Insectosaurus who isn't voiced by anyone because he doesn't have anything to say.





Sci-fi fans will have fun counting off the references to myriad classics -- "Close Encounters of the Third Kind," "Invaders from Mars," "The Fly," "The Creature from the Black Lagoon," "The Blob," "Mothra" and "Attack of the 50-Foot Woman," for starters -- and noting a few clever bits and pieces (Kiefer Sutherland, as General W.R. Monger, riffs on George C. Scott in "Dr. Strangelove").





The trouble is, once the introductions are over, the filmmakers can only launch their desperately limp plot: The White House turns to these monstrous superheroes to save the planet from evil Gallaxhar (Rainn Wilson), a squidlike creature with four eyes and twice as many legs, and a one-eyed tin robot to do his dirty work for him.





Ginormica gets a kick-butt finale, and is a much stronger character -- in any number of ways -- than the movie's president. (In a genuinely witty casting touch he's voiced by Stephen Colbert.)





That may be good politics or at least a sound marketing decision from the studio's perspective -- it's been awhile since a family animated feature produced a genuinely strong female character (unless you count "Coraline," which was way too scary for my family) -- but Susan's self-esteem is an awfully long time coming. iReport.com: What do you think of 'Monsters vs. Aliens'?





(Bizarrely -- and maybe it's just my imagination -- Gallaxhar bears a passing resemblance to President Obama. I wonder ... would that make Susan/Ginormica a surrogate for Sarah Palin or Hillary Clinton?)





Visually, too, "Monsters vs Aliens" is undistinguished, although its shortcomings may be disguised if you seek out the 3-D version. Funny how 3-D movies tend to produce two-dimensional characters
What is the title of the movie? who produced the movie Who is voiced by Reese Witherspoon? who is the movie aimed at What is the name of the lead actress?
"Monsters vs. Aliens." Dreamworks Animation, Susan Murphy your kids. Reese Witherspoon),
question: What is the title of the movie?, answer: "Monsters vs. Aliens." | question: who produced the movie, answer: Dreamworks Animation, | question: Who is voiced by Reese Witherspoon?, answer: Susan Murphy | question: who is the movie aimed at, answer: your kids. | question: What is the name of the lead actress?, answer: Reese Witherspoon),