"Mean Girls" is indeed an exaggerated version of reality, but its depiction of the brutality and ridiculousness of high school and the need to find and stay true to oneself within a social construct manage to ring true. It does not stray away from or gloss over the dark humor that high school inevitably draws out nor is it apologetic in its over-the-topness. The result is a hilarious, well-written/performed film that is unpredictable and worth seeing.
Lindsay Lohan shows us once again that not only is an actress with range and a deft comedienne, she is also extremely likable and charismatic. Other stand-out performances go to Caplan and Franzese as well as Tina Fey (who plays a teacher), Amanda Seyfried (as one of the Plastics, Karen), and McAdams. McAdams, probably best known as the title character in "The Hot Chick", is an actress who continues surprise me with her great comedic skills (don't believe me? Watch her deleted scenes from "The Hot Chick" DVD. I liked them better than the whole movie!!).
All in all, this flick is great fun and more well-done than might be initially expected!