Pros:
Awesome tool for getting actionable data on what your competitors, or your client's competitors, are doing online. Having PPC data along with SEO data and keyword data in one app saves a ton of time doing research. The app works, the data is solid (as solid as estimated PPC ad spend can be) and the value of the app is outstanding. Very easy to monetize the monthly spend on this app.
Cons:
This really is an online tool that offers a wide spectrum of resources. My only critique would be on organic keyword rank tracking. For marketing initiatives based on the objective of growth in organic search rankings, it is beneficial to see what page your listing falls on for specific keywords. Although SpyFu offers customized keyword lists, They are not segmented by the specific Search Engine (Go ogle, Bing, Yahoo) that keyword ranking applies to, as far as I am aware. There are other tools that offer this online, but it would be nice to have this feature under the same umbrella of SpyFu tools.
Overall Experience:
My main goal is to spy on competitors keywords and backlinks, which I then use as an idea bank to create keyword possibilities for my firm. It's effective at finding other keyword opportunities I might not have thought of. I then add them to my keyword bank and eventually select the most applicable keywords for my clients. Numesko had the paid version for quite some time and am considering re-upping my subscription because I am now seeing the value of having an all-in-one SEO tool, which I would use not just for keyword generation and competitor research, but also backlink outreach and managing the entire SEO project.