Put 3 phones next to each other with similar hardware design, Android, Symbian, iphone
ask 10 non-geeks to use the phone (mid 30's non tech workers) to do tasks such as
- make a call, answer a call
- use calender to make an appt
- add/edit/delete a contact
- create a playlist of music
- turn on/off bluetooth
- download a popular app (Shazaam)
- browse the photo gallery
- give marks on how "smooth" the UI is

Symbian is just too clunky when compared to the other 2 for everyday tasks for "average joe".