To sum it all up: as a simple, but easy-going animated crime/caper pastiche, The Nut Job provides enough in the way of colorful entertainment.
The Nut Job takes place in the fictional city of Oakton, where the animal residents of a local park work together to collect enough food to sustain them through the winter. That is, save for Surly the Squirrel (Will Arnett), an aptly-named curmudgeon with a loner streak, who instead prefers to get by with assistance from his mute sidekick, a scrappy mouse, whom Surly calls Buddy. However, due to a series of unfortunate circumstances, Surly is banished from the park by his peers - led by the authoritative Racoon (Liam Neeson) - and must navigate the treacherous inner-city, where vicious street rats and dangerous human technology lurks around every corner.
Fortune smiles on Surly when he stumbles upon Maury's Nut Store, a place that has all the food he and the other park animals need to get by through the cold months ahead. Of course, first the various little critters will have to get by King (Stephen Lang), a convict and his cronies, who are using the shop as a front for their own special "job."
Nut Job is based on the 2005 short animated film "Surly Squirrel" made by Peter Lepeniotis, who also co-wrote and directed the feature-length treatment of his original cartoon. Furthermore, the ToonBox Entertainment project (budgeted at $42.8 million) is the most expensive animated film co-financed by South Korea, which accounts for the insertion of a certain world-famous Korean pop-song (and its singer) in the movie - elements that are rather incongruous with the film's setting (sometime in the 1940s/50s) and throwback style to the gangster Looney Tunes/Merry Melodies cartoons produced by Warner Bros. back in the mid-2oth century. That said, Nut Job is a decent animated crime/caper for younger audiences - one that shouldn't test their parents' endurance too much.
Lepeniotis and his Nut Job co-writer Lorne Cameron (Brother Bear, Over the Hedge) have put together a pretty rudimentary screenplay with regard to story beats and character development, yet they also manage to include some intriguing concepts (self-dependence vs. serving the greater good, or the usefulness of false idols) in a manner that tends to be disorganized, yet still remains accessible to kids. Likewise, Surly's personal arc in the film is mostly predictable, but it does manage to deviate somewhat from the standard blue-print, as do a few of the other narrative threads.
As for the manner in which the film juxtaposes the "Nut Job" with the robbery being committed by the humans, it's mostly for comical effect, rather than something more sophisticated (see: how animals' "thievery" is depicted in Pixar's Ratatouille). Regardless, that additional, if thin, slice of intelligence helps to elevate The Nut Job and carry it though the weaker sections of its storyline.
The same goes for the exaggerated physics of the movie's world, as well as the stylized world design (which resembles 2D techniques realized in 3D) and the action sequences that take advantage of the minuscule protagonists' unique perspective. (It's almost enough to make up for the film's many puns involving the word "nuts" - and be warned, there are a lot of those.) 3D viewing isn't a must, especially for those who prefer it when animated characters and objects appear to literally jump off the screen (see, for example, the Despicable Me movies), since Nut Job tends to go more for depth of field and immersion. On the other hand, that also means the 3D visual elements tend to not be distracting and are most effective during action scenes set atop buildings or moving vehicles. So, as whole, the 3D ticket upgrade option depends on your preferences.
Will Arnett's broadly gruff tones works pretty well for Surly, even though the character is a pretty standard (though fully-rounded) heart-of-gold type. Katherine Heigl and Brendan Frasier voice two of Surly's fellow Squirrels, Andie and Grayson, and the pair are equally adept at voice-work, despite being type-cast as fairly two-dimensional personalities (the "strong" female and good-natured but clueless stud, respectively). Perhaps the animal most worthy of praise is Buddy, because his characterization is dependent on pantomime and his physical mannerisms - which are done pretty well, all things considered. Finally, the supporting cast is serviceable, if mostly unremarkable with their vocal performances, including Liam Neeson as the power-hungry Racoon, Stephen Lang riffing on gangster tropes as King, and Maya Rudolph as the criminals' pug, Precious (one of the better side players).
To sum it all up: as a simple, but easy-going animated crime/caper pastiche, The Nut Job provides enough in the way of colorful entertainment. Just don't expect to remember much of it over the year ahead (save for the eyebrow-raising sequence that runs over the start of the end credits - which will only make sense if you know about the film's Korean backing).
The Nut Job is now playing in 2D and 3D theaters. It is 86 minutes long and is rated PG for mild action and rude humor.