Is Just Write Checks designed for the visually impaired? If not, can a blind person use it?
No, the software is not recommended to be used by Visually Impaired because it doesn't have support for. I've checked the Help Guide, but there is nowhere mentioned about visual impairment support.
However, in user you have Narrator that can help you to navigate through software.
Read more here: http://windows.microsoft.com/en-us/windows-10/getstarted-hear-text-read-aloud