It's wonderful that this app is free! The information is provides is so helpful for me. I am able to implement the suggestions they provide and there is nothing that forces you to use their professional services to fix the issues for you.
It's a great model because those who can't fix it themselves aren't left helpless, and those like me are able to use the tool to locate errors that are otherwise missed. The scans are comprehensive and each item is appropriately explained in an easy to understand fashion.
I also like the ability to change urls and scan each one individually. This control is helpful so we can optimize every page on our website, not just the homepage.