Some hate 'em, some love 'em.  I use them sometimes because if you say something sarcastically, it helps let the reader know that it was in jest so there isn't perhaps a language barrier that causes them to take offense.  

The ones on this site are a bit hard to make out.  Pretty sure it's just like buying a new font...just got to look for one that plays well with the page.  The one you have now doesn't work very well - hard to make out expressions so you have to roll over it to see what the person means.  Simpler is better in this case.