The ease in which you can setup your server with just one click from Microsoft Azure portal! It's very fast compared other solutions I've used before like Filezilla or WinSCP etc..
Nothing really bad about this software but maybe we should be given more options when it comes down loading time? Maybe give us some kind option that would not require restarting everytime there are changes made by our customers (like adding many users). We started using CFTPServer after being recommended so much online because they're offering free trial version during their launch date event where all new products will go live at once - hence saving lotsa money since most companies don't want monthly subscription fees anymore :).