Receptional_Andy - 3:49 pm on Mar 9, 2009 (gmt 0)

The price is fairly high for a keyword research tool, but I have no experience of it myself. Quality is really dependent on the dataset a tool has, and what processing it applies to that data.

If you're happy with the free tools available and are getting the results you want, then you've probably already answered the question as to whether there's a convincing argument for you to start paying.