Chicken Alarm does nothing that your iPhone's built-in alarm doesn't already do; but it is cute, effective, and fun to use, so it can be an effective replacement for those that enjoy using it. There are not necessarily any issues with the app, but because it lacks additional tools and features, there are limited situations in which it will be a viable replacement.
After installing Chicken Alarm, you must set your alarm. Do so by tapping on the large yellow chicken animation onscreen and choosing when it should go off, whether snooze is enabled, and how frequently it will repeat. These are, unfortunately, the only options you have. You cannot set multiple alarms like you would with the iOS alarm clock, nor can you turn on the slide to turn off features that iOS has, making it entirely too easy to accidentally turn off your alarm instead of hitting snooze. While you can back it up with an iOS alarm clock, as well, there are few reasons to use it if you do so.
Chicken Alarm is a fun app, designed to be cute and effective, while not necessarily over delivering on any of the core functions needed to make it an effective app. If you are enamored with the cuteness of the app, don't mind the lack of alarm diversity and snooze options, and tend to wake up on the first call, then this is a good app that will work well for you.