There are two problems that I hear:
1) It's Juvenile
2) It's Confusing
The juvenile part I hear more regarding my tweets than blog posts and I have to agree. I tend to end many statements with !!! Why do I use 3 !!!? It is juvenile and I will work on stopping. It wouldn't be a problem if I didn't do this far so many tweets. For those that follow me on twitter, I apologize and will mature in my tweets in the future.
The confusing part makes even more sense. I've been told that I sound angry when I mean to sound excited and excited when I mean to sound angry. Without being able to speak it, the emotion that I am trying to convey can easily be confused with the use of a "!".
So what do you think? When you write are you a big user of the "!" or do you avoid it? Do you find it to be confusing or juvenile?