- Asynchronous I/O support, channels, JSON
- Partials, Lambdas and Closures
- New style testing
- Viminfo merged by timestamp
- GTK+ 3 support
- MS-Windows DirectX support
For a more complete list and details, have a look here.
The TL;DR summary: Vim provides a lot more power now to plugin developers, so we’ll be seeing a boost in both new functionality and old ways getting better.
Here is a mandatory Slashdot discussion with your usual Vim vs. Emacs flame.
P.S.: Emacs has recently released a major update too …