What makes a good password?
Good passwords consist of a combination of letters, numbers, and symbols.  Good passwords should be long, easy for the user to remember, but hard to guess.  Most attempts to steal passwords use brute force, so the length of the password is more important in terms of the compute needed to discover it using brute force methods than would be special characters.  Special characters used in short passwords also prove ineffective because there are many well know leet dictionaries that provide common special character insertions.