Because great content requires a deep understanding of the main idea (e.g., “ac repair houston”) and the supporting subtopics that require coverage (e.g., “central ac vs portable ac systems”) and the common issues that users seek answers for (e.g., “freon,” “refrigeration loops,” “coolant refills,” “troubleshooting”), the effectiveness of a keyword reporting tool is only as strong as the SEO pro using it.
Before you can put it to use and start making Long Tail Pro pay for itself, you first need to understand exactly what Long Tail Pro does and how it will benefit you. The number one benefit and feature of Long Tail Pro is that it helps you analyze the competition in Google much faster and more effectively than if you tried to do it only using free tools.
Basically, Google shows the autocomplete suggestions whenever you start typing anything into Google search box. It is in Google's best interest to show the most relevant keywords in the autocomplete suggestions. Keywords that would help Google to retrieve the most relevant websites and help users find the most relevant content for their search query.

Google prefers to not share long tail searches in this tool – because the tool is designed for Google Adwords advertisers. If advertisers bid on those long tails – they would have less competition and therefore pay less for the Adword, and therefore Google would make less money e.g. bidding on the term weight loss for girls under 18 is cheaper than weight loss. 
Google's AdWords Keyword Planner tool is another common starting point for SEO keyword research. It not only suggests keywords and provides estimated search volume, but also predicts the cost of running paid campaigns for these terms. To determine volume for a particular keyword, be sure to set the Match Type to [Exact] and look under Local Monthly Searches. Remember that these represent total searches. Depending on your ranking and click-through rate, the actual number of visitors you achieve for these keywords will usually be much lower.
1 – I’ve found a niche with low competition and good CPC . but the thing is the while doing competition analysis. I observed that most of the sites that are in the top 10 serps ranking are small ecommerce site selling their own product or sites like niche specific classified ad site with low and thin content. What are your suggestions ? Should I go for such keywords ?
I would like to get LTP but I’ve read that people have some issues according to Keyword Planner and Moz. Do you still recommend this tool? How accurate is it’s data comparing to previous versions? Does Keyword difficulty still works as it should? Maybe it’s better to wait untill some stability of this software? I don’t want to waste money for some tool which doesn’t work properly.
Because someone who is looking for something that specific is probably a much more qualified searcher for your product or service (presuming you're in the blogging space) than someone looking for something really generic. And because long-tail keywords tend to be more specific, it's usually easier to tell what people who search for those keywords are really looking for. Someone searching for the head term "blogging," on the other hand, could be searching it for a whole host of reasons unrelated to your business.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website.  In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC).  I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.