According to SPARC (the Scholarly Publishing and Academic Resources Coalition), "Open Access is the free, immediate, online availability of research articles combined with the rights to use these articles fully in the digital environment."
Because of the nature of Open Access publishing, many scholars view OA journals with skepticism. Learn how to evaluate OA journals to be sure you are citing scholarship from the most trustworthy sources.
When reviewing an open access publisher or journal for quality and legitimacy -- the following should be considered:
From Principles of Transparency and Best Practices in Scholarly Publishing.