Christel Fein has published "Multidimensional Journal Evaluation of PLOS ONE" in Libri: International Journal of Libraries and Information Services.
Here's an excerpt:
All 28,852 documents published in PLOS ONE during the 5-year-period between 2007 and 2011 have been extracted from Web of Science. This data provides the basis for the evaluation. The data concerning the conducted evaluation has been collected as well as analysed multidimensionally, to demonstrate more fully the complex structures and aspects of the impact, prestige and position of PLOS ONE, and to assess the information and data obtained as specifically as possible. Based on Juchem, Schlögl, and Stock (2006) and Haustein (2012), a framework of five dimensions of journal evaluation has been applied, in which each contains several metrics to analyse scientific periodicals from various perspectives, i.e. journal output,journal content, journal perception, journal citations, and journal management.