There’s no easy answer to this question, as it varies by industry, the age of your business, and a number of other criteria. But for new businesses, even if all you care about is rankings, I see reviews quickly becoming the dominant ranking factor in local search: the number of reviews of your business, the star rating of those reviews, and the content of those reviews.
To that end, you should invest heavily in customer feedback.
But customer feedback can help your business in so many other ways within marketing and beyond it. If you are not yet intentionally gathering feedback from every customer, now is the time to start.