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).
This is slightly more complicated than it used to be, because you have to actually create a live AdWords Campaign as part of the process! This puts many people off, as it looks as if you have to actually advertise in order to use the tool. You don’t — you can just setup the campaign and then pause it before it runs so you don’t have to spend a penny.

Keyword Overview looks at the entered term on its own and addresses expected searches per month, the difficulty of competing against Page 1 results for the same term, a rough estimate of organic click-through opportunities (versus paid ads and non-organic positions on the search engine results page), and the perceived priority that the user should assign to optimization for this term, where the higher the score, the higher the demand and a lowered level of competition.
Trying to rank for the keyword “Best Headphones” will see your post, page, or article buried in the depths of a billion search engine pages, and it’s never going to surface in the top thousand pages, let alone page one…ever! But going for a keyword, or Long Tail keyword phrase “What are the Best Headphones for Sleeping” will stand you in better shape to get somewhere close, or even on, the first page.
We prefer and suggest Long Tail Pro to all our clients. Long Tail Pro is the best long tail keyword research software online. I use their software for researching keywords for everything from social media marketing bios, to page and blog post titles, to headings (H2, H3, etc.), to meta descriptions, to YouTube descriptions, to content/articles, and so much more!

* Please note our tool currently assumes Google having ~ 83% of the market, with Bing + Yahoo! splitting the remaining 17% of the market. Actual market conditions may vary significantly from that due to a variety of factors including: search location, search market demographics, how much marketshare mobile search has relative to desktop in that particular vertical, etc.
One possible problem is that although the Keyword Planner has some cool new features (including integration of the Google Traffic Estimator, which will be retired too), as of this writing, the indispensable Exact Match and Phrase Match features are nowhere to be found! Whole books will become useless without these, so I hope Google will eventually port them to the Keyword Planner. Nor do you see the “Include specific content” option, which is a life-saver for the adult industry, which spends the most on Google PPC.
For the first few months, there was certainly a transition period.  However, the new team was able to take over the reigns fairly quickly.  A big reason for the quick transition is because I had automated most of the business already.  So, the fact that I was stepping away didn't make a huge difference since all the sales, marketing emails, and many other details were already happening on an automated basis.