That being said, I feel like the replies here are a bit of a hugbox. As far as the app's value itself goes, I don't see any benefit of this compared to an accomplished.txt file. In fact, a txt file is better because it covers more use cases and has a simpler interface(just start typing).
Why should I use this rather than a notepad? Look for features you can add that would be useful for manipulating data about accomplishments. Find ways to set the app apart.
Accomplishment ranking could be one useful feature. Then you could list even the tiny accomplishments, but if you want to just look at the big accomplishments you can always sort based on ranking to clear out the noise.