Pretty useful. I did some quick mods and went from a 89 to 98 pretty quickly which isnt too bad.

Only complaint is that I had to click to expand out the page speed problems. You might want to add a horizontal triangle or some other visual indicator there is more to look at. Either that or expand them all by default but allow people to close them.

Only issue was that it suggested I could minify my JS and gain a 0% reduction in a few cases.