There are very few animated films that can truly compete with Disney/Pixar and DreamWorks movies. Sadly "Planet 51" is not one of those films.
The setup is based on an alien planet whose culture is stuck in the 1950s. Their alien paranoia is suddenly kick-started into high gear when Chuck, a NASA astronaut, arrives without warning and turns their world upside down.
The entire movie is based on Chuck's landing on a foreign planet and his attempts to get back to his ship before it leaves without him. Since Chuck is, technically, the alien, he is greeted with prejudice and fear by the planet's native inhabitants. He does receive aid from a select group he eventually calls his friends. The adventure Chuck and his friends experience in order to get him back to his ship before it's too late may keep kids interested, but not most adults.
Visually, "Planet 51" looks very appealing to the eye, but once the novelty of the 1950's on an alien planet wears off, there isn't much left.
This is merely a mediocre animated comedy with a mediocre plot and average humor. Having Dwayne Johnson voice lead character Capt. Charles T. Baker really wasn't necessary. Neither was Gary Oldman, Jessica Biel or Sean William Scott.
Advertised as a family movie, adults will not get much enjoyment out of it.
2.5 buckets
