The problem is mainly the lack of visual cues; there is no way to tell that sliding the main screen to the left will toggle the alarm on in Rise, or pinching a list in Clear will minimize it and take you up a level in the hierarchy. It’s not obvious, and what’s often called mystery meat.
I have never liked apps like Clear. While nice to look at, I can never remember which way to flick or swipe. And if I haven't used it in a while, I am completely lost.
Via Daring Fireball.