Google is still the biggest search engine on the Internet used by thousands of customers search for businesses and by businesses looking for customers.
Google Maps is a huge benefit to businesses and customers alike. The Google Map Pack provides golden real estate for promoting your business; it's the list of businesses that appears in search results for "businesse near me". It's one of the best ways to drive online and local traffic in the form of prospective customers.
Think of it as the digital equivalent of a physical billboard or signage pointing the way to your storefront. That's why it's important that it is optimised and well maintained.
The fact that your customers get to leave notes, in the form of ratings and reviews, on how they expereicned your business is a golden opportunity to add some independent social proof of how great your business is.