Tart is an uninspired mess. First, in terms of character construction, there is a lot of mention of these characters' age, but they act like grown-ups, complete with the suit jackets and sipping on whiskey -- they're not just grown-ups; they're cliched grown-ups. And are they rich? They act like it, mentioning their parents as magnates of big businesses, but Cat's argument about the money for the dance and their surroundings are decidedly lower class at times, a mixture that produces confusion, not complexity.
Second, the dialogue is stilted and delivered like amateur actors are auditioning for community theater.
Finally, the plot is thoroughly predictable until it turns into a Lifetime movie at the very end; the final resolution has almost nothing to do with the rest of the film's conflict.
Overall, this film is without a redeeming element; even Bijou Phillips's beauty can't serve as a refuge from the shit that surrounds her.