One of our clients is very demanding.  We ran into the following limitations
- It would be nice if all dialogs were editable.  The only screen on the prereq screen that can be edited is the introduction screen.  If we were to try and remove a product instead of installing one (You can see my other posts) the dialog does not match up with what is actually happening.  
- It would be nice if we had a if file DOES NOT EXISTS option for prerequisites.