Long legs. Blond hair. A sexy smile. A foul mouth. No filter. Edge. Cameron Diaz has it all in Bad Teacher, one of the many R-rated comedies released over the summer and now slumming its way onto DVD and Blu-ray. Too bad the movie doesn't have the same punch.

Diaz plays Elizabeth Halsey, a carefree junior high teacher who, after being dumped by her sugar daddy, returns to school to save up money to get a boob job so she can land the man of her dreams. Her misguided ideals put her at odds with another teacher (Lucy Punch), especially after a handsome new (and rich) teacher (Justin Timberlake) is hired, but Elizabeth will do anything to get her way. Jason Segel also stars as a gym teacher.

Bad Teacher is a mildly entertaining and somewhat funny comedy that works more often than not. Directed by Jake Kasdan (Walk Hard) and written by Gene Stupnitsky and Lee Eisenberg ("The Office" and the utterly unfunny Year One), the movie is meant to be an edgy dark comedy. It succeeds to a degree, but as with so many mainstream dark comedies, it lacks bite. The characters talk the talk, but the filmmakers stay clear of anything too offensive or detrimental to the bottom line. Mainstream audiences like happy endings, and a happy ending is what they get.

Even though the movie itself lacks edge, Cameron Diaz does not. She carries the film with an uncharacteristically dark performance. In fact, the performance is Diaz's best since 1998's There's Something about Mary. The character's actions are restrained by the script, but Diaz gives it her all. She's vulgar, insidious and yet strangely likable, a protagonist who has few redeeming qualities.

The supporting cast also does a good job. Jason Segel, as always, plays a likable love interest, though since Elizabeth hates his character for most of the movie, "love interest" is inaccurate. Justin Timberlake is mildly funny, but has been better in other movies. Lucy Punch is spot-on as the so-cheerful-she's-creepy antagonist.

Bad Teacher isn't a great movie. It could have been funnier, it could have been edgier. Should have been, too. But Cameron Diaz is so wickedly good that she makes the movie work. Bad Teacher is far from perfect, far from a classic, but it's worth seeing. At least sort of.

Review by Erik Samdahl.