From what I can tell, they're on about the same level as far as plot and character development go, only with less purple prose and overblown religious imagery, and a LOT more heterosexual sex. (Though I did stop reading the Chronicles after Memnoch, so I could be wrong about that last part - I do remember the nauseating relish with which the "Lestat drinks what's-her-face-who-just-happens-to-look-just-like-a-younger-thinner-Anne-Rice's menstrual blood" scene from Memnoch was written...)