As you describe, @Override creates a compile-time check that a method is being overridden. This is very useful to make sure you do not have a silly signature issue when trying to override.
For example, I have seen the following error:
public class Foo {
private String id;
public boolean equals(Foo f) { return id.equals(f.id);}
}
This class compiles as written, but adding the @Override tag to the equals method will cause a compilation error as it does not override the equals method on Object. This is a simple error, but it can escape the eye of even a seasoned developer