There are some issues we know about, but were not fixed until now:
a) Mentions may cause problems when you use more than 1 in one line (@"username") - you may have problems erasing them with backspace if you use a lot of them in one line. If that happens and you encounter such problems, use backspace until it stops. Then, when you're stuck, use space to break the mention. Now you should be able to erase it. You'll need to do that with every mention in a row. When used in a new line they seem to work just fine.
b) There is not "spoiler" button, but you may use spoiler tags. To do so, use:
[spoiler] content goes here [/spoiler]
c) The forum doesn't work well with text copied from Wrod (and probably some other modern software) - it's besst to write message directly in the forum text editor OR copy text from word to the notepad first and then copy it here (to erase formatting)
Whilte it's not perfect, I hope it will be enought for the forum to be functional.