The method getName() was defined and it's implementation would change the order in which the migration would be processed. It would cause discrepencies between the file order in a file browser and the order of execution of the migrations.
The getName method as been removed | set final and new getDescription method has been added. The goal of this method is to be able to provide context for the migration. This context is shown for the last migrated migration when the status command is called.
The --write-sql option would only output sql contained in the migration and would not update the table containing the migrated migrations.
That option now also output the sql queries necessary to update the table containing the state of the migrations. If you want to go back to the previous behavior just make a request on the bug tracker as for now the need for it is not very clear.
MigrationsVersion::VERSION used to be a property. The returned value was fanciful.
It is now a a function so that a different value can be automatically send back if it's a modified version that's used. The returned value is now the git tag. The tag is in lowercase as the other doctrine projects.