It's not really doing anything a phone app can't do. There are some $20 alarm clocks that have gimmicks to get you out of bed that are quite effective, so no need to pay $100 for this, unless you just want it because you like the design or the themes.
Sleep as Android has a mode that makes you solve math to turn it off, there's nothing I hate more early in the morning than math but it's quite effective in at least keeping me from turning the alarm completely off, leaving me with snooze as the only option. That used to be a problem when I was using the stock alarm app.