For the most part, the English language keyboard is fine for people typing in, well, English, but UniChar is a useful tool for those who need to expand their characters now and then. The keyboard offers up the entirety of the Unicode character database, giving users a quick way to search up and implement all the accents, squiggles, and symbols that they might need.
UniChar is likely to be most useful for people who have to communicate in more than one language frequently. The basic keyboard will still be suited to English, but users can quickly search through the database through a variety of different methods to find other languages' accents. One of the most interesting searches is the draw feature, which lets users sketch a picture of the symbol they're looking for if they don't know the name.