I'm posting this a lot, but I'm not just trolling. I'm trying to get people to grasp the fact that UI is the reason for Apple's success.
Everyone else treats the UI as an afterthought or for whatever reason is incapable of designing a good one. The UI should be of primary concern.
This is particularly true of mobile apps. As your device and its screen gets smaller, UI design becomes exponentially more important. A bad UI can be tolerated on a 1920x1080 desktop, but not on a phone or a small pad.