Ive had the Hemingboard for Mac and iPhone for a few hours now and I can say it is a tremendous fun for a curious or linguistically inclined person (btw, I love the apps name!:-) Dunno how to rate the merits (the functionality) because its my first alt keyboard and Im not generally good at writing on my phone (after all these years. Oh well.).
Lady Eliza Doolittle about Hemingboard: Synonyms,Rhymes,Puns in Your Keyboard, v1.7