Provides links to price estimate tools from Google AdWords. That Google AdWords tool showed the necessary bid to rank #1 for 85% of queries, and roughly how much traffic you could expect AdWords to send you based on that bid price and ad position, though, as mentioned above, Google has obfuscated their data in their interface for everyone but longtime AdWords advertisers.
Ever since Google announced the impending demise of the AdWords Keyword Tool and their preference for its new avatar – the Keyword Planner, yet another hot discussion has sprung up in the SEO community. This time, strong adherents of the free-for-all ideology are riled at Google’s decision to make the Keyword Planner accessible only to marketers who’ve explicitly signed up to Google’s AdWords (which is one step more than having a Gmail account), taking it closer to being a paid tool in future! I don’t see this as a hindrance, because most other keyword (or other) tools require you to create an account and sign in before you can use them, even if they’re free. But if Google does it, we have reason to pounce on them, don’t we?
You can also filter by query, which is useful when looking at branded queries, or when looking at specific words. For example, only show keywords that include the term "SEO". The graph also allows you to spot trends in across the available metrics and compare week-on-week or month-on-month. This can help you to drill down and monitor progression over time, allowing you to answer questions like "have my branded keywords received more clicks in the last month compared to the previous month?", "has the CTR improved?", "did average positions in Google improve?".
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. 

As you might imagine, the ability to completely see and study how the competition is ranking for certain keyword phrases in your niche has significant value for any company. Tack this on with its other features, and Long Tail Pro makes a ton of sense for content marketers. And like I said before, the price tag is very low compared to some of the tools I’ve seen out there, with a one-time fee (NOT a monthly fee) of $97 and a 60-day, money-back guarantee.

The link back to googles API is crap – it keeps coming up with password authentication which renders it virtually useless when trying to find your own rank. Sells you the software initially. But then tries to sell you a load of stuff afterwards which effectively tells you the first version you have already paid for is useless without the extra “bonuses”. Not a nice way of doing business
The limit on manual keywords could be higher.  I personally wish we could input 10,000 keywords at a time, instead of 200.  However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input.  Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).