In my experience, free books are of equal quality as other books from the same source.
Baen's free books and Amazon's commercially published freebies are of the same quality as any commercially published novel. Some good, some bad, but all showing at least basic competence.
Self-published freebies are another thing entirely. The good ones are as good as anything else on the market, the bad ones are really bad. It's a slush pile and not everyone wants to wade through slush. Commercially published books are generally better, because someone's already gone through and weeded out all the absolute garbage.
|