This isn't in itself a reason to reject iFonz - the reason this software is so poor is that the programmer, talented as he or she is, doesn't seem to understand the basic concepts of testing and usability. Over the months considerable added features have been incorporated into iFonz, yet the software continues to run poorly. Earlier bugs have been cleared up only for new ones to take their place.
With Spb Mobile Shell 3 and Windows Mobile 6.5 now available, it seems bizarre to drop the very identify of Windows Mobile in favour of the stylings of a rival platforms. I don't see anyone offering BlackBerry Storm skins.
Of course, this is the beauty of Windows Mobile - the very fact that you can create something like iFonz 2. However in this case, the software simply isn't good enough for prolonged usage.
iPhone stylings + bad programming = poor application. Stay well clear.