The trailer was funny enough, with an astronaut so full of himself thinking that his planetary visit was an open and shut case, only to discover that it's inhabited and he's the alien in the truest sense of the word, like a fish out of water trying to make his way home lest he becomes an experimental subject.
And the aliens, well, are just like us, with plot conveniences such as having the same mixture of atmospheric gases like Earth's, and hey, the green things with four fingers on each hand speak English too! They're city folks with a penchant for 50s musical oldies (that pepper the soundtrack), with a whole host of modern day, earth-like references all over the place in a desperate attempt at being recognized for being smarty-pants. Unfortunately though it tries too hard to be funny at every turn, and it only brought about the occasional mirth.
It's about time that filmmakers realize that pumping a film with too many references for its own good, is something of a tired formula. You'd wonder when such references will seize, to allow a good story to shine. Planet 51 suffers from too much wink-wink moments, complete with blatant rip offs that bring too much attention to themselves. One look at the pet named Ripley and resembling like a Xeroxed replica of an Alien complete with acidic pee, you're likely to roll your eyes. Or how about that robot probe that functions and looks like R2D2/WallE and comes without dialogues but plenty of whirrs and beeps while going about doing cutesy stuff?
Despite a relatively A-list voice cast with the likes of Dwayne Johnson (who doesn't sound like the real deal if you ask me), Justin Long, Gary Oldman, John Cleese, Jessica Biel and Seann William Scott, Planet 51 felt like a Frankenstein monster, stitched together from ideas of other films, and plastered together forcefully to try and make the narrative work. Characters too are a little boring and one-dimensional, with little heart.
Bottom line is, CG graphics and copycat characters don't make an animated film entertaining. A sincere story does and this one is found lacking, and too talky too for kids to enjoy, in my opinion.