They’ll show you information like how many external links the site has, the number of Facebook and Google+ shares, estimated visits per month, and its page authority. All of this is valuable intel that can give you insight into where your page could potentially rank against them, without needing to do more research with a separate tool or on another page.
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.