"Certainly not a must see like the other Pixars, but it's good enough."
The story revolves around Mater, rather than Lightning McQueen, a mixed decision in my opinion. On one hand, Lightning McQueen is a bland character, with little personality. And Mater, while much more interesting and defined, is also extremely one dimensional, and that really shows when he becomes the star of the show.
Mater is mistaken as an American spy by two secret agents, Flinn McMissile and Holly Shiftwell. Mater then takes part in many missions, while the two secret agents have no idea he's just a regular tow truck. In the meantime, Lightning McQueen is on a World Grand Prix in hopes of beating the c*cky, Francesco. There's a bit more to the plot than this, but that's the gist of it.
The film certainly looks like a Pixar film. The animation is easily Pixar's best; appearing more detailed than that of Toy Story 3, and the various race/spy scenes give the movie a chance to show what it can do. Some things look impeccably real (in the last 20 minutes of the film, take a look at the trees).
The film sounds like a Pixar movie too. The musical soundtrack is performed masterfully by Michael Giacchino. Also, the voice talents have been selected carefully, just as in all Pixar films. The original voice actors are back (though due to the death of two characters, Fillmore's voice has been replaced and Doc is deceased), though most of them get few appearances. Also, John Ratzenberger (who gets a role in every Pixar film) has an infestimal role in this film: only two lines.
So, the film sounds and looks like a Pixar, but it doesn't feel like one. Compared to the other Pixars, the story is weak and disappointing. Also, there is none of the heart and emotion that made the other Pixars so lovable.
There's little adult-kid balance, so most parents won't be watching with their kids, which is completely opposite of other Pixars, where parents may enjoy the film more than the kids.
I said earlier that this film is more like a Dreamworks movie. This is because of the lack of emotion, the shallow story, and the kid appeal. Even the humor is a little more Dreamworks oriented, a lot of it being roll-your-eyes kind of humor, and there's even some potty humor. That's not to say you won't laugh; there are plenty of amusing bits, but overall, it pales in comparison to Pixar's previous efforts.
Concluding, this is Pixar's worst film, hands down. However, it's still a great film, although flawed. It's certainly not a must see like the other Pixars, but it's good enough.
Just don't do this to us again, Pixar: I won't be quite as forgiving.