1) Addition of OData BDC connections 2) Apps for SharePoint in BCS and BDC models can be packaged as apps for SharePoint. 3) External List has been enhanced which includes performance improvements, data source filtering & sorting, Exporting external lists to Excel. 4) BCS exposes REST APIs for web and mobile development.

OData Support as data source
Eventing FrameWork for external notifications
Provides also alert capability for external lists,
BDC models scoped for app level, not to farm level
External list enhancements
Performance improvements, Data Source Filtering, Sorting, Export to Excel
CSOM API