I can tell you from experience that the program does work incredibly well.. I've been using it myself for about a year now. It's definetely well worth the investment. But keep in mind that this certainely isn't the 'holy grail' for getting traffic. Social bookmarking is just one big tool you need in your toolbox for bringing alot of traffic to your site. I would also recommend dropping alot of comments in other peoples blogs.. posting on forums, answering relevant questions on yahoo answers.. PPC(pay-per-click) advertising is also great if you can afford it.. etc etc
There are many ways of driving traffic to your site.. I would absolutely recommend getting bookmarking demon program, it works wonders. But keep in mind thats only one important side of the rubix cube. It isn't the end all be all. Good luck!