The most obvious advantages are the following:

• unlimited and free access to publications
• higher citation rates for Open Access articles
• increased visibility of research (even for non-researchers)
• better indexed by search engines
• Secure long-term archiving of publications when uploaded to certified repositories or publishing in renowned Open Access journals
• advantages by using digital documents in research and education (Open Educational resources)
• collaborative work, use of automated data and text analysis
• authors are in full control of their copyright

A more comprehensive depiction of the advantages of Open Access publishing as well as arguments against some reservations may be found here:

An important question for researchers in regards to Open Access is the quality of an Open Access journal.

The initiative thinkchecksubmit has discussed this question and created a checklist.

Should most of these questions be answered with a “yes”, this Open Access journal may be fit for a publication.