I received an iPad Mini for Christmas. It has more or less replaced my Retina iPad and given me cause to rethink my workflow. The iPad Mini's size and weight make it a much more convenient device for daily use. The Retina iPad's sharper screen and greater power make it better suited to complex tasks. Is there room for both in my life? I doubt it very much.
This raises an interesting question: at what point do different devices become redundant? Prepare to ask that repeatedly in the coming years.