"Open Access is free, immediate, online availability of research articles with full re-use rights. It involves making all scientific research content available for anyone anywhere in the world to read, to access, and to build upon so people can do interesting things in new ways with the material."
Source: Open Access Explained! video created by PhD Comics
Myth: Open Access sources are low quality and do not have peer review.
There are open journals that are low quality. There are OA journals that don't have peer review. There are OA journals that are high quality and have peer review. OA is like traditional publishing in this respect. There are high quality journals, low quality journals, established journals, and up and coming journals. A good place to look for an Open Access journal is OASPA, which has strict standards for admission.
Myth: Access is not a problem
Not even a top research institution like the MSU can afford access to all scholarly literature. As journal prices rise much faster than inflation or library budgets, more journals are cancelled.