Hello Malcor
Yes, I also had to configure the VMA according to http://pubs.vmware.com/vsphere-51/topic/com.vmware.ICbase/PDF/vma_51_guide.pdf "Configure Unattended Authentication for Active Directory Targets" on Page 15.
It is my understanding that even the VMA is joined to the AD the Linuxpart of the VMA doesn't know your personal account which is defined in AD. That's of course the reason why you can't login with ssh to VMA with your personal AD account.
Because I wasn't very happy with the VMA 5.1 and the syslog funcionality was removed we will setup a dedicated syslog server and use vCenter Orchestrator to make mass updates on ESX Hosts.
Manuel