The Last Airbender is a film directed by M. Night Shyamalan, in much the same way that a steaming pile of crap on your lawn is "directed" by your dog's anus.
If your English-speaking movie is an adaptation of an English-speaking TV show being marketed to English-speaking audiences, you have absolutely no excuse for pronouncing all of your character's names wrong. Unless you've never actually seen the show, which...really makes a lot of sense, come to think of it.
Aang is the title character, a charming mystic youth called an "airbender" whose irreverent charm and happy-go-lucky attitude caused the complete and total genocide of his people. His name is pronounced like the last syllable in "boomerang". It is not pronounced like "hung" without the "h".
General Iroh is pronounced "eye rho" is not pronounced "ee rho". He offers wisdom and guidance to many characters in the show, followed by rough, unfriendly sex in the back of a van by the looks of him.
Sokka is pronounced exactly the way it looks in the show. In the film, it's "soak a". He's the wacky comic relief in the series, which would usually mean he's the really fucking annoying one in the movie - but apparently even "annoying" is too much character depth of Shyamalan, so he's just a block of human-shaped wood surrounded by special effects like everybody else.
Many parts of the show's story were blended together for the film. And that's understandable. Movies are a short-form medium: Some condensing of the plot and some missing characters are to be expected. If done skillfully, an adaptation can still capture the essence of the show for the movie-going audience, while maintaining the spirit of the original work for fans of the series. It is not done skillfully in The Last Airbender. It's done more like premature ejaculation sex, where one party (movie-goers) is left confused and ashamed, while the other party (fans of the show) are left enraged and disappointed.
In the series, Katara and Sokka discover Aang sleeping in an ice cocoon, whereupon he awakens and befriends them. And aside from the fantastical elements, it is a simple, believable interaction - much like how real children might behave.
In the movie, the two find Aang trapped beneath the ice, whereupon they awaken him by smacking him with a boomerang over and over again. A baffling, kind of dickish interaction - much like how mildly retarded Australian jerks might behave.
Rescuing the Earth Benders
Whatever else you might think about the show, at least it thinks the elemental, magical aspects through completely. For instance, in the series, the Earth Benders are held captive in a POW camp on an oil rig out to sea. This is to keep them from using their Earth mastery to escape - a simple detail that makes the world a bit more believable.
In the movie, the Earth Benders are imprisoned on...Earth. Just left there, on land, standing all over the one thing they and only they can use as a weapon. The only reason they didn't instantly and immediately beat their captors to death with mockingly large Earth fists? They weren't inspired enough. Enter our hero, who gives them a stirring speech about freedom that reminds them - oh yeah - they're literally standing on top of billions of tons of weapons they can use.
Half the Shit at the Northern Water Tribe
In the series, a water master named Pakku initially refuses to teach Katara how to use the powers of water, because he's just kind of a sexist dick. Much later, and only after eventually realizing that they're related, he caves and reluctantly teaches her. This shows that even the powerful and the wise can have massive character flaws that serve to humanize them. Further, a love triangle crops up between Sokka and a girl named Yue. Though she is engaged to be married, Sokka pursues her anyway. Again, this is not the "morally right" course of action, but it adds depth to an otherwise shallow character.
The ultimate lesson being: Even the best of us can be selfish, prejudiced or vain - it is the human condition.
In the movies, Pakku immediately and unhesitatingly teaches Katara... because he's wise! That's what wise dudes do; they teach crap and junk to whomever. Also, Yue is single, so Sokka can just up and hit that shit up for some weird, twisted elemental sex with no moral repercussions whatsoever.
The ultimate lesson being: Life is as easy and uncomplicated as it is awesome, water-bros!
Presumably they cut the alternate ending where they just all go surfing and high five into a wacky freeze-frame.