I like that I can mark up a page and see all the usability issues I see. I also like that I can take screenshots and add them to the page. I dislike that the interface is a bit clunky. It's not very intuitive. I think it's a great tool for anyone who wants to make a quick "first pass" usability review of a website. I use it to make sure a site is user-friendly. I can mark up the page and make notes about what I think needs to be fixed. I can also take screenshots of the page and add them to the page. I can also add links to external resources.