samba - May 2015 - raising the functional level of the domain and forest in Samba4?

Good morning friends !!!

What is the purpose of raising the functional level of the domain and forest in
Samba4?

Today use the 2008 server to set my samba.

Is there any real advantage in carrying out this process? I using 2008 can raise
it to 2008_r2? It has some of the 2008 difference to 2008R2?

Sincerely,

Gabriel Franca