For me, just knowing that the Hemingway App exists was almost enough to help me keep my writing precise and concrete, like Papa himself would want. But the app did help me find long sentences quickly, and it was nice to see adverbs and passive voice in case I wanted to do anything about them.
This app is great for writers who are working on making their sentences shorter and more precise. It provides a way to get instant feedback on sentence length and complexity without having to ask someone else for input (and without having to hope Word understands what you’ve written). I used the app to help me make sure I was writing simply in passages that would later be translated into other languages. The simpler the original sentence, the easier the translation process will be.
But the app is not a panacea — you still have to use your own writing talent to improve those red- or yellow-highlighted sentences. And you definitely have to use your own judgement. Not all passive voice is bad, not all adverbs add bloat, and sometimes a well-crafted but long sentence is more effective.
Still, as a reminder to aim for simplicity and clarity in your writing, the Hemingway App excels.