The main change in the release is greater modularisation, allowing only the parts of the framework required by a particular app to be loaded at runtime. You can read more on the team’s blog post.
This is the last major release of Enyo 2 and in a separate post, the development team layout some thoughts on possible directions and considerations for version 3.0. Developers are urged to contribute their opinions on the Enyo forums. Enyo is the main framework used for LuneOS. We will update with any comment from the webOS Ports team and urge anyone developing apps for LuneOS to contribute to discussions about the future of Enyo. Here’s the webOS Nation comment thread and a discussion on coding with 2.7 here.