You never need to use this class for normal workflow operations. The only reason to use it is when you are rehosting the designer or need the SaveWorkflowImage function to create an image of the workflow. This is a sublcass of a WinFormUserControls.
One caveat to be aware of is that the code needs to run under a thread with an STA ApartmentState. If not you will receive errors messages that the DragDrop registration did not succeed while creating the WorkflowView.