Imagine ET reversed and restaged in that newfangled family film mandate, CGI, and you've got some idea of what to expect with Planet 51. Is it as good as Spielberg's exquisite suburban sci-fi fable? No way. Does it offer a better than average action adventure featuring interesting animation and characters you will care about. Well…

Sadly, it seems that the three first time filmmakers in charge of this project -- Marcos Martinez, Javier Abad, and Jorge Blanco -- have studied exclusively at the Shark Tale/Shrek school of cartoon humor. Jokes revolve around the adolescent obsession with various body parts (alien or otherwise), there are dozens of plodding pop culture riffs (which seem weirdly out of place on a far off distant planet), and the main players are simplistically drawn and voiced with all the verve of a B-lister cashing a paycheck.

Dwayne 'The Rock' Johnson stars as astronaut Capt. Charles T. Baker, the kind of cleft chinned, chiseled jaw narcissist who seems to populate the cinematic version of NASA. Arriving on the title world, he discovers a surreal alien society living like it's the 1950s. Naturally, they believe Baker to be a space invader, which stirs the interest of the military, including the maniacal Gen. Grawl (Gary Oldman). Luckily, our hero is befriended by Lem (Justin Long), a typical E-Teen with dreams of landing the hot honey in town (Jessica Biel). With their help, Baker tries to avoid capture while seeking out his ship, desperate to get back to Earth.

If the story sounds overly simple, that's because it is. Oh sure, screenwriter Joe Stillman (responsible for the first two installments in the Mike Myers/gassy green ogre franchise) thinks he's offering some sly social commentary when a long haired hippy-like alien named Glar (Alan Marriot) shows up, clearly meant to hint at a growing counterculture movement on Planet 51, but that's about the extent of the satire. Instead, we get the standard slapstick, decidedly off color gags, and one cringe worthy retread of that horrid dance craze from 1995, 'The Macarena'.

Still, there's at least one redeeming element here: a quirky little pet named 'Ripley' that looks suspiciously like a miniaturized version of the beast HR Giger created for Ridley Scott's Alien. It even pees acid. After that, however, the movie plays like one long chase scene, Barker having to find a missing robot and return to his ship before he is stranded forever -- or worse, caught by Grawl and his gang. Yet we never really fear for our lead's safety, never once imagine that the otherwise stereotypical plot won't lumber along, looking for the numbers its meant to follow on the way.

While it's not as awful as last year's cosmic themed failures -Space Chimps or Fly Me to the Moon -Planet 51 is endemic of what's wrong with the computer generated genre. It's dull and lifeless, moving inertly from point to point without offering much that's memorable or amusing. Indeed, the biggest sin committed by this mediocrity is its lack of genuine fun. Not even the little asides (communities laid out like crop circles, alien audiences lining up for the latest smash hit horror film, Humaniacs III) can elevate this otherwise average effort.

With Pixar plotting a new masterwork every year and other studios trying to escape the commercial confines of the category, Planet 51 seems like a step backward. In fact, it often feels trapped in the same sanitized era it celebrates. What could have been a nifty spin on the 'stranger in a strange land' routine becomes nothing more than a humorless pile of space junk.

Please don't phone home during the feature presentation.