I started using Screpy about a week ago to track my own and clients' website rankings.
I have used and am still using a couple of similar tools for SEO tracking and management. (Ranktracker, Labrika, SheerSEO, Screaming Frog, etc).

What I like most about Screpy is the fact that the interface is intuitive and easy to use but at the same time gives me all the power I need to effectively manage my site SEO. Others give more detailed reports (Labrika) but can be overwhelming at times.

As a bonus, you also get site uptime monitoring and site speed tracking which you can surely get in separate tools but it's really handy to be able to centralize and include that in one single report.

So for me, it's an easy 5 taco rating because of the power combined with ease of use.