There are loads of note-taking apps for smartphones, and lots of them are really good. However, I'm always hunting down new ones to see if they outperform my favourites. Writeily manages that really clever trick of being very basic, and thereby being very useful; but if you want bells and whistles you should look elsewhere.
Text formatting options are truly minimal. If you want something to appear as a header you put a hash in front of it. For bold highlighting in the text, you must surround a word or phrase with two asterisk characters. But you don't need to bother with all that, really. If you are the kind of person who just wants to get your ideas down fast, then Writeily could be ideal.
Without the faff of formatting, the words can flow. Trust me on that, I am a convert to Writeily precisely because it lets me be productive really fast. You can add the finer details of formatting later, after you have shared your notes either as text or, because you can write HTML in Writeily, as HTML.