I don't know why anyone would use this instead of JassNewGen with TESH support.
I mean, TESH has syntax highlighting, supports vJass, folding (which is quite useless anyway though), autocomplete, and parameter highlights. As well as a searchable library of all constants/functions. It is quite useful.
I just wish for the day where we could code like in a Visual Studio environment. Something that I hope gets added to TESH is that is recognized functions that you create yourself (probably will never happen), so that the parameter hints and custom functions are highlighted as well. That's kind of the only improvement that could be made to it. Smarter folding would be nice too.
Unless this text editor can have all those things, I don't know why someone would use it. (Except if dont want to load up NewGen to code or don't want to DL NewGen... which is a silly reason)