It's about half as good as a non-specialist human proofreader (see my post above) for a fraction of the cost. While that's not sufficient for some documents, I

It's about half as good as a non-specialist human proofreader (see my post above) for a fraction of the cost. While that's not sufficient for some documents, I consider it (in addition to my own eye for detail) good enough for things like client proposals and my academic work (grad student), not to mention all the real-time (chat, email) applications.