You can collect product reviews on your product pages and manage them in Admin > Product Reviews or on a per product basis in Product Manager > Reviews tab.
You can also share reviews across products via Product Manager > Reviews tab.
3rd Party Reviews Via Reviews.io (formerly Reviews.co.uk)
You can also collect reviews via Reviews.co.uk and blend these into your product pages along with your own product reviews.
Google Customer Reviews
You can also collect reviews via Google's customer review service.