Samba4 really is a MS Active Directory substitute. With new Samba 4.0.7 there are important improvements in interoperability with MS files. Please, include them in future updates. Thank you.
Release Notes for Samba 4.0.7:
http://www.samba.org/samba/history/samba-4.0.7.html
Heads-up in late next month:
Tuesday, August 20 - Planned release date for Samba 4.0.8