UBL is rated number four on a prioritized list of citation sources in a key article by noted search marketing blog Direction SEO. The author notes:"For Local SEO purposes, having local citations for your business is considered to be one of the most important factors in getting your Website to rank higher in Google’s newly modified local results section. A local citation is a link from an “authoritative” directory, review site or internet yellow pages site linking to your Website. In other cases, the citation can be a listing for your business on another site that matches (and therefore validates) the information on your site such as the address or phone number."
UBL is rated fourth for citations after Google Places, Yelp and foursquare, and ahead of Yahoo, Local.com CitySearch and Bing. See the full list and article here: http://www.directionseo.com/seo-tools/local-citations/