This study, conducted by the Kaufman-Wills Group, dispels the notion that Open Access journals do not carry out peer review or copy-editing. However, many Open Access journals conduct peer review purely in-house, and fewer do proper copy-editing for style and grammar.
By and large, Open Access journals are younger than subscription journals, though some of them are unexpectedly long-established. It is therefore unsurprising that most of them have not yet achieved the same level of impact as more established journals.
The study was sponsored by the Association of Learned and Professional Society Publishers (ALPSP), the American Association for the Advancement of Science (AAAS) and HighWire Press/Stanford University Libraries.
The Facts About Open Access: A study of the financial and non-financial effects of alternative business models on scholarly journals (ISBN 978-0-907341-30-7) by Kaufman-Wills Group. PDF: http://www.alpsp.org/publications/FAOAcomplete.pdf