There are a lot of alternatives on the App Store to the built-in note-taking tool provided by Apple on the iPhone. That doesn't necessarily mean those apps are good alternatives, and in the case of IDoNote2, it is unclear what advantages you are supposed to gain by using this app, instead of Apple's.
The idea behind IDoNote2 is elementary--take notes and view them in a clean white interface. Unfortunately, nearly every aspect of the app performs poorly. From the fuzzy, low-resolution interface to a cluttered and cramped input screen and an organizational system that lacks any sorting options--IDoNote2 is as bare bones as you're likely to ever get with an app like this. That said, it does work and you can take notes that are then stored on a clean, blank screen. If you prefer to use something that doesn't look like a legal pad, this is a great way to do it--just not necessarily in the package presented by iDoNote2.
Some apps strip away features and succeed because they are plain. Others are simply underdeveloped, presenting fewer features but without the benefits of simplicity. This is not necessarily a bad thing, but it can be very frustrating when trying to take notes on the go or access and share them from your phone. While the intent behind iDoNote2 is great, the execution is not quite polished enough to be effective. You might consider an alternative.