You'll find some information here [webmasterworld.com]
and
here [webmasterworld.com]
Which may help you make up your mind.
It really depends upon the product or service you're offering as to whether the directory is of use.
Perhaps some will come out of the woodwork with positive or negative (Videoman excepted as he's got it in for the uk directories ;) )
As it happened I had already been listed with them for several months on the first page for my area and category (due to a lack of other listings) with absolutely no enquiries received!
Their site seems obstructive to finding what you want. It appears to be structured in a way to make it easy for telesales people to earn their commission!