This is a great plugin. It's descriptive and addresses some of the major issues caused by AJAX for those unaware. Most times with ajax the url doesn't change and the fact that it automatically changes the url is KEY to its success as a WordPress plugin. They do a good job of letting you know what to do to resolve issues.
I started a music blog and needed an effective solution to allow the audio player to play uninterrupted across pages. This did it. I found it much easier and custom to implement than Jetpack's infinite scroll.
It does take a little bit of stumbling around to utilize it effectively in a custom theme, but once I got it rolling it saved me a lot of time.
It would be nice to have a cleaner field to add the reload scripts, as well as style the page loading info, but I haven't purchased it yet so I shouldn't expect a damn thing. I also think the code comments albeit funny maybe a little unprofessional. I think it also heavily clutters up the header portion of my site.