I tell my SEO (Search Engine Optimization) clients that “Five-star Google reviews are like gold”. One client listened and encouraged customers to write reviews . . . which his customers did. Unfortunately, while they scored my client as a five-star vendor, their reviews included no text. None.
These five-star reviews with no text are, as far as I can tell, worthless. Google places them at the end of review lists, and seems to give them no value. They seem to provide no SEO benefit.
Moral: To receive SEO benefit, ensure that your customers include some text when they create a review of your business. A review of three or four sentences is fine.