Well it is a new edition of Gimp, so some radical changes. Default Legacy modes are there for backward compatibility.
If you are using Gimp for art then one useful difference is the fix for RGB semi-transparency blending.
see: https://www.gimp-forum.net/Thread-Gimp-2...ng-problem
While you are still hooked on Gimp 2.8 remember that when saving in Gimp 2.10 remember to change all layers to legacy or your .xcf will not be readable in Gimp 2.8
If you are using Gimp for art then one useful difference is the fix for RGB semi-transparency blending.
see: https://www.gimp-forum.net/Thread-Gimp-2...ng-problem
While you are still hooked on Gimp 2.8 remember that when saving in Gimp 2.10 remember to change all layers to legacy or your .xcf will not be readable in Gimp 2.8