Not at all! Though all online content needs to be thoroughly evaluated for quality, many of the openly licensed learning materials created and used today are just as good, or better, than traditional publisher textbooks. There are a growing number of studies that show that students are doing just as well or better in their courses that use OER. The vetting process is essentially the same as traditional textbooks.
What is so great about OER is that the open licenses allow for information to be changed easily as the world changes and new research and current events become important. Traditional textbooks fall short here, often lagging behind what is currently happening in today's world and releasing expensive new editions whenever they are updated. It is important to remember, however, that each discipline is at a different stage of growth in OER; some disciplines have many high-quality resources to choose from while others are less developed.
A few OER repositories have begun including peer reviews and faculty showcases, which highlight how the OER they selected worked for them and their students. As the open education movement gains popularity, more ancillary materials are being created, like test banks and homework systems.