Update: I’ve now been using Long Tail Pro for 5+ years. There are now many different keyword research tools and lots of people prefer some of the newer tools. Admittedly – Long Tail Pro had some hiccups and went through some rough times as they transitioned ownership and introduced the newer cloud version. But – all of the bugs and kinks have been worked out and Long Tail Pro is now better than ever! I’m happy and proud to be able to continue to use and promote Long Tail Pro as my keyword research tool of choice.
It would be great if you can provide comparative analysis of this tool with Google Keyword Planner. Since you’re using this tool so you can provide best comparison. One differentiation which I understood is that this tool works for yahoo and bing as well whereas Google keyword planner works only for Google but Google being a dominating search engine, gives the highest returns, so only this reason may not be enough to buy it.