Wizard Steps should have a "Value" or other similar property so that they can be located server and client side by something other than title and/or index using a FindByValue method. Wizard Step titles and indices can be easily changed as the Wizard is modified, thus breaking any code that makes use of title or indices to get a reference to a step.
Also, and it has been repeated elsewhere, users need to be able to access the Wizard navigation buttons server-side in order to manipulate them (text, enabled/disabled, visibility, etc.). I'm not really sure why such basic functionality wasn't part of the initial release of the control. I mean, why would you release a control that provides a number of features which improve on the existing ASP.NET Wizard control, and yet is missing a bunch of important features that the ASP.NET Wizard control has. It just puts developers in a bind, having to decide whether or not to invest the time and energy of figuring out how to implement your control, only to find that they can't do some basic thing after investing that time.