What are people looking for on your site? These terms are keywords in the vocabulary of your actual audience and should definitely be added to your keyword list. Do not forget to look at the keywords people filled in that didn’t get any results: this was stuff people were expecting but didn’t find. You can look into the results of your internal search in Google Analytics at Behavior → Site Search → Search Terms.
Quick question… in your review you mentioned focusing on some products like ProductNamethat are spelled as Product Name and are low competition. My question is how would you tackle a review using a keyword like that? Would you make that the primary one that is misspelled? Would you mix them with the spaced spelling and correct spelling? I’ve found some good ones and would appreciate some direction on how you’d handle writing a post to rank for the spaced keyword?
The reason I sometimes use this facility with the GKP is to find volume amounts for the keywords I’ve chosen. But, these days, it’s not so important. As long as the Long Tail Keyword makes sense and is something I would put into a search engine, then it’s good enough. Sometimes the most blazingly obvious keywords are often over looked by eager, trying-to-be-clever marketers. Sometimes you need a tool to highlight them.

4. Set post-search filters. After your keyword suggestion fetch is completed — which might take a while if you input a lot of seed keywords — you need to filter your list. You can: filter out keywords that don’t include buyer modifiers like “best”, “buy”, “purchase”, “discount”, “review” (it’s possible to input one or more words in the filter field at the same time: just separate the words with a comma); add a minimum and maximum amount of LMS; set a minimum amount in “Suggested Bid”; and check for only high “Advertiser Competition” keywords.

The experts love SEMrush, but will you? Take the tool for a test drive and decide for yourself. For a limited time I'm giving all my readers an exclusive one month free access to SEMrush PRO. You'll get unrestricted access to all the tool's features. If you decide SEMrush is not for you, cancel anytime during the one month trial and you won't be charged a penny. 
The primary difference is that Long Tail Pro is a big time saver over MS. With Long Tail Pro you are able to enter in multiple seed keywords at once (rather than just 1 with MS). So, instead of entering in 1 seed keyword, waiting five minutes, then going back and entering in one more; you can enter 5 seed keywords (for example), hit generate and then see all the keyword ideas at once!
As for the history of the company, as I explained, I created Long Tail Pro back in 2011.  At the time, I was creating tons of niche sites and was doing alot of keyword research and content creation.  I was trying to figure out what types of keywords would rank quickly in the search engines, specifically Google, and I was frustrated with the other keyword research tools (in particular Market Samurai) out there.