If you know your Muppets, you will remember that in The Great Muppet Caper, Fozzie, Kermit, and Gonzo are flying to England in a cargo hold. Fozzie's cage is labeled BEAR; Kermit's, FROG; and Gonzo's, WHATEVER.
This movie is all about the Whatever. It turns out that Gonzo is an alien, and he discovers that his people are trying to find him when his breakfast cereal starts to send him messages. From there, it is a short step to Covnet, a secret government agency, trying to grab him for their own purposes.
Throw in Miss Piggy aspiring to a television career, liberal quantities of Rizzo the Rat and Pepe the Prawn, talking sandwiches, and revealing glimpses of Muppet home life, and you are well on the way to the latest Muppet extravaganza.
No Muppet movie is complete without cameos from contemporary stars, and Muppets From Space might have the most ever seen (including an unexpected 'Dawson's Creek' interlude). In the usual knowing, referential way, visual quotes from other movies are also liberally dropped into the stew: amongst them, Independence Day, Men in Black, James Bond, and (my favourite) the mashed potato from Close Encounters of the Third Kind. Thankfully, they also dispense with the cute child and songs that marked the mediocre Muppet Treasure Island.
Promising ingredients, then, and it's a small disappointment when it proves impossible to sustain the comedy evenly over the full length of the film. But it's impossible to hate the Muppets, particularly when aliens from outer space play funk.

Elmo is a children's movie from the Sesame Street gang. It is important to get that out of the way before we go any further, because most movies ostensibly directed at children actually slip in plenty of jokes or references directed at the adults who are accompanying the anklebiters. (Obvious examples are Toy Story and the Muppet movies.)
Elmo is not like this. It makes no concessions to adult sensibilities, and it even has Bert and Ernie stopping the movie whenever things get bleak, to reassure the audience. (The one glorious exception to the 'children first' rule is an exchange between Bert and Ernie about movies with sad endings that people actually liked, which would go completely over any child's head.)
The movie is about Elmo (of Tickle Me fame) who loves his blanket very, very much. Unfortunately, when his friend Zoe wants to share his blanket, the two of them have a falling out, and the blanket is lost in Oscar's trashcan and passes through a portal to Grouchland. There, it is seized by Huxley, the evil villain who Does Not Share (played with childish glee by Mandy Patinkin).
Naturally, Elmo (who is apparently meant to be the equivalent of a human three-year old) has to face his fears in tracking down his blanket, learning important lessons along the way, and touching people with his own special brand of wisdom.