Noteastic Notepad, despite its overzealous name, is a somewhat mediocre app. Yes, it does the job, but when compared to other similar programs you come to realize it doesn't have any special features. Those it has are well implemented. It's a good looking application with basic features. It's simple and easy to use and in case you either don't like the original app that came with your OS, or simply don't have it, Noteastic Notepad could prove to be a suitable replacement.
The first reason that comes to mind is tied to the fact that it displays ads. Sometimes it's worth having those if the offered functionality is indeed jaw-dropping. In this case, however, there is little to talk about functionality wise. The app performs like any other basic virtual notepad. It allows text editing, importing, saving and printing.
You can save your documents in a proprietary format, a format that would otherwise be obsolete if this Noteastic Notepad would not exist. You could save important files this way, as a form of encryption or protection against data theft. Unfortunately, it's as easy to download the app as it is to save documents in its proprietary format. It wouldn't really be a long term solution.
The other feature that makes it distinctive is the possibility you have to change the background color. It's not really something that will revolutionize the notepad app industry, but it does stand out. Interestingly enough, the text color adapts depending on the shade of color in question. Black text for lighter backgrounds and white for darker ones.
Noteastic Notepad is an application that you'll probably not come to use. It's useful only if your original text editor went missing or is broken beyond repair. The few common features it has are well implemented. The application has no bugs or stability issues and the distinguishing features are welcome, even though they do not expand on the app's functions.