Do you change many settings? I rate what's not categorized (mostly netflix -2 and my project sites as +2) but leave default settings almost whenever I can. Its ability to give useful reports immediately is what I like about it.
A bit, but so much for me ended up being generic browser usage (I also use a web-based browser) that not all that much was useful. I think it might have been a bug in RescueTime that didn't always capture the information on the site visited in the browser.
Anyways, I don't think about it much, I don't use it, and I don't miss it.