Not a toy at all. As a CS ISU grad, and a friend of a researcher in the C6, I can attest that this has more uses than a toy. For instance, John Deere has used this to model new virtual cockpits for upcoming tractors. They can see if all controls are within reach and in reasonably intuitive places. If they aren't, they can change their positioning using a wand to grab them and move them. It has (or plans to) also been used with other caves to collaboratively develop models and see them work, such as a model of an engine.
It is quite an impressive feat. You can pick, grab, and move things around just like they are right in front of you. It is more than just 6 flat panels. You also wear lcd shutter glasses and make those 6 panels turn 3D. So when reaching out to grab things they are exactly where you would expect them to be.
However, it CAN be used as a toy even though that isn't it's primary purpose... I have also seen Quake played in the C4 (precursor to C6). Pretty cool to say the least.