Clients are used to their traditional tools (very likely Excel) and to bring them to using new one might be the problem. But! As your clients still plays an important role in your content management process – approval, their cooperation is irreplaceable.
In ZoomSphere we pay a lot of attention to make thinks clear at the very first sight. But as it is massive system, it might be confusing for the newbies. 🙂 I have made a tiny Publisher guide for them, to not get lost.