Usernames longer than 14 are not valid, but allowed to be created in new VM wizard.
When creating a new VM from the portal, an admin user name greater than 14 characters can be created, but it is not valid. The result was I could not remote into the VM as the user credentials were rejected. It wasn't until I went and tried to reset the password did I receive the validation error that the username I had selected was too long. I had to delete the VM and recreate it with a shorter username before I could RDP into the new Virtual Machine.