Instructions on migrating your code are here:
The advantages of migration are
- latest versions of Candid, Motoko, and other dependencies in the sdk
- Support for type inference in your frontend code
- broader bundler support
Here’s a writeup I wrote for the changes back when they were in version 0.7.7, which was ultimately promoted as version 0.8.0: Dfx 0.7.7 Changes | Kyle Peacock's website