I run a multilanguage website, but not every theme or plugin comes with all languages I need. Loco Translate makes adding additional languages or fixing existing typos much easier!
The only problem I found so far: Sometimes language files will not be created with the right filename (either in the wrong path or only with the language code as filename and not using the theme/plugin name) and have to be renamed manually. But after renaming the files, it works fine, since Loco Translate will use the und update file properly even though it did not create it under that name.
Update: This is not the case with the latest version any longer - it works fine.