Anne Rice's interview with a vampire is a very interesting take on the vampire tale. While many of the vampire staples are there; the ancient life, feeding off of blood, vulnerability to sunlight, and need to sleep in coffins, most of the other weaknesses are missing. Religious iconography have no effect on them, garlic is an irritant but nothing more, and staking them through the heart does not guarantee instant death.
My favorite aspect of the movie is the take there is on the vampire's personalities, there is a very nice balance between the two main characters, Lestat and Louis. Louis is a very emotional, whiny character, and though it can be annoying at time, the fact that the story is told from his point of view gives a very nice counterpoint to the action happening within. When Lois is made a vampire with such suddenness that it is not completely clear if he was willing or not. His first feeding is violent and distasteful for him, causing him to become a "vegetarian" vampire, feeding only on animals, and to develop a very strong dislike for Lestat, who he views as crude and unappreciative.
The dynamic between Lestat and Louis is very interesting. Louis constantly lambasts Lestat for not indulging in the pleasures of live. He views Lestat as crude and hateful of all life. The interesting thing, however, is Lestat indulges his every whim, killing as he pleases and taking delight in the morbid nature of his life. Louis shows much more restraint in his life, being more of the traditional, overly emotional and regretful vampire that is common in modern stories. A key scene is when Louis stumbles across a child who's mother died of the plague and feeds off of her, almost killing her. Lestat comes in and encourages Louis to finish her off, dancing with the mom's corpse. Louis finds this grotesque and flees, this becoming a clear moment in his mind of Lestat's complete disrespect of life. What he doesn't think of, however, is that while Lestat had his morbid dance, he did feed off of a child and leave her to die alone.
Lestat is a necessary foil because it shows the hypocrisy of Louis. Louis kills people every night, but whines about his cursed existence and how he is just a victim. Lestat is there as a reminder of "we are monsters, we literally feed off of death, so stop beign so dramatic and enjoy it."