You can have many reason to create Google Shop for your business however these few may give you an breif idea what you can get if you have set up Google shop.
More product focusedGoogle Shopping provides more product specific performance information. By providing your complete product inventory directly in AdWords, you can structure your campaigns by product groups and categories to give you greater control over your bidding strategies.
More granular control with custom labels and campaign prioritiesCustom labels are a new, structured way to tag your products in your data feed with attributes that matter to you, such as ‘margin’ to separate your high- and low-margin products, price range or promotional status. Google Shopping Campaigns now offers 5 levels of custom labels.
More advanced reporting capabilitiesGoogle Shopping Campaigns now offer you the ability to view your performance data by product or product attribute. Since performance metrics are associated with the item and not the product group, you can filter and segment data by your product attributes. This includes Google product category, product type, brand, condition, item id and custom labels.
Access to competitive metricsNew to Google Shopping is the ability to gain valuable insights into your competitive landscape. You now have access to the estimated average CTR and Max CPC for other advertisers with similar products. Although the performance data is anonymous it gives you an accurate benchmark on what your competitors are doing and enables you to make more strategic decisions.Source