With 9 smash films and nearly 15 years of film making under their belts, one might assume that Pixar would celebrate in grand fashion with their 10th theatrical release. Instead, with Up, Pixar has delivered their most unconventional and absurdly layered film to date.

Carl Fredricksen, the 78 year-old widower at the heart of Up is an unusual protagonist. Arthritic, grumpy and boxed in by life, he is partnered by the youthful and exuberant “Wilderness Explorer” Russell as he sets off for adventure to South America.

Up hooked us with its visual signature of a tiny house being lofted into the air by tens of thousands of balloons. But the story takes an unusual left turn when Carl and Russell finally land in South America.

Surrounded by strange vistas and a lush, but harsh environment, the duo is greeted by the affable and endearing Dug, the talking dog. Things only get weirder from there as the pair encounters a 13 foot tall iridescent bird, a crazed long-forgotten explorer and dirigibles.

The unusual details of the story are what sets Up apart from previous Pixar films. But it’s the rich metaphors and subtext that make Up truly engaging.

At its core, Up is a movie about lost opportunities, obsession the struggle to “fix” the past ruins the opportunity to enjoy the present.

Each of the main characters deals with this in some way. Russell uses over achievement and collects Wilderness Explorer badges to attract the attention of his absent father. There is one small space left on his sash full of accomplishments – a badge for “Helping the Elderly” and it’s missing directly over his heart.

Carl is trying to make up for lost time by going on the adventure his never got to go on with his wife. But since he can’t bear to leave behind his belongings and all of his memories, he takes them with him by setting the house aloft. The house becomes a symbol for his wife – something he has to learn to let go of by the end of the film.

Muntz, the story’s villain, is corrupted completely by his obsession to trap a rare bird in order to bring it to civilization and repair his damaged reputation. His relentless pursuit is ultimately what leads to his literal downfall.

These story elements are framed beautifully by the bevy of mini-documentaries among the Blu-ray’s bonus materials. The character studies for Carl and Russell are particularly insightful.

Carl, for example, is one of Pixar’s most stylized human characters and the decision to make him so was very deliberate.

Animators noted that, as a septuagenarian, Carl’s movements would very limited. His physical restrictions mirror his world view as every shot Carl appears in before going to South America he is placed inside some kind of box. He is either looking out of a window or the camera is looking at him through a door frame. He lives a very interior life. As a result, Carl himself became very square shaped, with hard-edged and inflexible features. A boxy character living in a boxed-in world.

Alternatively, the rotund Russell is almost egg-shaped. This reflects the nurturing he requires in the absence of his father. It becomes Carl’s instinct to take care of him.

Another fantastic bonus feature is the original story concept behind the 10 minute montage of “Married Life” – the emotional gut punch the starts the movie and leads Carl toward his adventure.

Assembled through animatics (animated storyboard concept drawings) and set against Michael Giacchino’s brilliant score, the alternate version of “Married Life” is just as emotional and affecting as what ended up in the movie – a testament to Pixar’s storytelling process.

It should be noted that there is also an excellent piece on Ciacchino’s contributions and how he transformed a simple, heart wrenching four-note melody into a glorious score.

Another great example of the lengths Pixar animators will go to capture their subject material is the engrossing :22 minute documentary “Adventure Is Out There,” which details how directors Pete Docter and Bob Peterson traveled with a team of animators to remote and nearly inaccessible tepius mountains of Venezuela.

Other features include audio commentary, the theatrical short “Partly Cloudly,” a second animated short called “Dug’s Special Mission” (that runs parallel to the main storyline in Up) and several other production features detailing the care, craft and precision Pixar executed to bring their unique vision to the screen.

The direct digital transfer to Blu-ray looks sumptuous as one might expect and the Blu-ray edition of the film comes with a digital copy and regular DVD copy as well (for your portable DVD player, I assume?)

Up may not be Pixar’s best film, but it is certainly one if it’s most ambitious. Despite its eccentricities, the emotional core of the story is potent – easily making it one of the best movies of the year.