Just as the proverb goes, what goes up must come down - and one day Pixar's seemingly unstoppable run of critically acclaimed animation blockbusters will end. Up, however, is not going to be the film that breaks the studio's successful run.

Living up to its simple title, Pete Docter and Bob Peterson's latest outing mixes heart-rending drama, side-splitting comedy and - of course - mesmerising imagery to powerful effect, conjuring a wonderful ride out of an airborne house, a petulant pensioner, a whining schoolboy and a phalanx of talking dogs.

At the centre of Up is Carl Fredriksen (voiced by Edward Asner), a sulky, retired balloon vendor whose house is surrounded by construction sites, and who is condemned to life in a dour nursing home. Determined to travel to the mythical (and fictional) Paradise Falls in rural Venezuela - a dream he and his recently deceased wife, Ellie (Elie Docter), had shared since they were children - Carl uses his remaining supply of helium balloons and sets sail for South America, only to discover a stowaway in the form of fumbling boy scout Russell (Jordan Nagai).

The main narrative alone provides a lot of laughs, with the pair's tortuous attempts to steer the floating house to its destination spiced up by an encounter with adventurer Charles Muntz (Christopher Plummer), who trawls through the Venezuelan tepuis for a rare bird.

But Up is more than just a barrel of fun: just like Wall-E, the studio's last hit, Up also has an intense emotional core. Book-ending the film are sequences that give shape to Carl's character: while Wall-E is best remembered for its dialogue-free scenes documenting the robot's loneliness, Up leaves its mark on audiences with a poignant montage charting Ellie and Carl's (above) life together, their joys and anguish conveyed with a subtlety one rarely finds in today's so-called family entertainment.

The same can also be said of the nimble way the filmmakers splice an ecological message into the proceedings. Carl's forced eviction from his land at the hands of property developers may be one of the more obvious signposts, but our changing perspective on our impact on nature is also explored. While Carl's generation seeks an 'adventure out there', Russell is more inclined to see the wilderness as something to be explored, which brings to mind, say, the domestication of animals and drilling for oil in the Alaskan wilderness.

With its myriad layers of meaning, all parcelled up with exquisite words and imagery, Up is simply exquisite entertainment.

Up is screening now