If you read Bryan Garner's articles in the ABA Journal or read any books on writing clearly, there are a number of recurring suggestions. Avoid the passive tense. Avoid adverbs. Avoid legalese or complex words when simple ones will do. Avoid overly long sentences. While I fall into the group that thinks these are good ideas, but not hard and fast rules, I do generally try to follow them in my legal writing.
The challenge, of course, is finding these issues in your writing. Microsoft Word's grammar checker is helpful, and it is what I often use as a first line tool. However, thanks to LifeHacker, I came across Hemingway today.
Hemingway identifies hard to read sentence, adverbs, words and phrases that could be simplified, and uses of passive voice. You can either draft directly in Hemingway or you can copy and past in what you have written. It will then highlight the problematic phrases.
The benefit of Hemingway is the visual aspect. Each type of problem is highlighted in a different color, making it easy to see where the problems are. I find this visual element to be much more user friendly than Microsoft Word's visual identification of problems - the green squiggly line that covers all grammar problems. Additionally, the ability to flag adverbs is something I don't believe Word is able to do.
However, Hemingway is limited to these five categories. With Word, you can check for jargon, the use - or non-use - of the serial comma (a must in my book), and numerous other stylistic issues. Additionally, the copying and pasting into Hemingway is undoubtedly more time consuming and likely to result in problems than just sticking with Word.
If you're looking to try something other than Word's grammar checker or really want a more visually understandable grammar assistant, then I would give Hemingway a try. Personally, I'm not sure it is going to be a regular tool in my toolbox.