Blackwell have certainly been churning out these 'companions' to the classical world over the last year or so and the quality varies immednsely. This, to me, is one of the better ones. Edited by Marilyn Skinner, this is an excellent anthology of modern scholarship on Catullus. Starting with the transmission of the text and debates about the ordering of the poems, it goes on to discuss issues of gender, genre, performativity, obscene invective etc, with detailed bibliographies on individual chapters. While ostensibly aimed at the school and undergraduate student, it's an excellent overview of the current literature with pointers on where to deepen your research.