I would say so yeah. Unfortunately I don't see anything but more fragmentation in this space without an Apple-provided controller API
I guess if you code your game so that it uses inputs 1 through 4 for directional joy-pad, and build in some way to configure or remap the other buttons in your game; that should give pretty good compatibility with most controllers? Most of them seem to use 1,2,3,4 for the directional D-pad thingy...
Yeah, the dpad/stick is really the only constant. What I do in my games is have an invisible menu in the options screen that shows up when you hit up/down on a controller, then you can select a preset from there. User-configurable buttons would be better of course, but I haven't got around to that just yet