It would be unfair to limit the film to one adjective. But charming is the first one that comes to mind. I really don't know how they did it, but the screenwriter Michael Arndt and directing team Dayton/Faris (Jonathan and Valerie, that is) have managed to create a movie in which we are simply so connected to the characters it's frightening. This is a very quirky bunch, and while their traits can be found in everyone we know, they are certainly extremely weird and I certainly don't know any families who are quite as odd as the Hoovers. And yet, we forge such a strong bond with each and every one of them, right from the opening pre-title introduction sequence - probably the best character introduction sequence I've seen since Magnolia. These people are just so real! It's unbelievable just how three-dimensional these characters are. They remind me of The Squid and the Whale - another recent movie that comes to mind when I think of this type of character development - these are just normal, regular people, and the filmmakers developed them as such in the most in-depth, well thought-out and just ingenious way possible.
That brings me to the second adjective: Realism. If you've seen the film you know that some pretty wacky things go on in it, but in the end, these people are just plain real. They are real human beings - at least we the viewing audience come to believe. If they weren't so incredibly well thought out and detailed and rounded, we wouldn't forge such a strong bond with them. But fact of the matter is, the Hoovers have quickly become one of the most memorable cinematic families. Their traits. Their flaws. Their dreams and ambitions. Their dynamics, mannerisms, nuances. Every tiny little detail about these people is just so incredibly portrayed.
Obviously, it would be unfair to say that a comedy isn't funny. When Little Miss Sunshine gets funny, it's hilarious - we're talking pitch-black dark and very quirky comedy, but it works admirably, reaching sort of a peak in the infamous, hilarious and totally wacky traffic cop scene.
The acting is. Simply put, amazing. You won't see any Oscar moments here, no characters that have some particular traits that require various forms of "method acting" to perform. This is simply actors playing a bunch of people who they are clearly quite unlike, but playing them as if they are. The shining star is young Abigail Breslin, who out-acts pretty much all of her older cast-mates. How she can embody a completely other character at such a young age is completely beyond me - and she's been doing it since age 6! Dakota Fanning, watch out! Paul Dano, the other young actor, also delivers an amazing performance. Myself being fresh out of that period of my life, I can say that his portrayal of a frustrated teenager - specifically in the scene where he just explodes (those who have seen the movie will know what I'm talking about) is just so true and realistic. Arkin is brilliant as the old grandfather, who is at once quite annoying and vulgar and at once the most human of all the characters. The three adult leads also deliver wonderful, nuanced performances - Toni Colette, who has quite a streak of wonderful performances in various films, particularly impressed me.