The new enhancements to Symbl.ai's Call Score API include 'Custom Criteria' and 'Scorecards', allowing for precise evaluation tailored to specific industries such as sales, customer service, healthcare, retail, finance, education, hospitality, legal, real estate, media, and entertainment. Custom Criteria enables users to develop detailed assessment criteria while Scorecards combine various criteria for comprehensive evaluations. The API now supports Streaming API for real-time conversations and Webhooks for call score status updates, improving overall customer experience and streamlining conversation processing.