There were high-end WinCE and Symbian devices with large displays and no physical keyboards (or sliders where keyboard doesn't encroach on screen size). To remind, first-gen iPhone was 3.5" @ 320x480 in 2007; for comparison, Dell Axim was 3.7" @ 480x640 in 2005, and by 2007 there were some WinMo handhelds with 480x800.
The thing that really made iPhone different was capacitive touchscreen, and the OS designed around that. WinMo pretty much required the stylus for many things.