Quarter-over-quarter (QoQ) compares this quarter to the one right before it. It catches changes in direction faster than the year-over-year view, but it can fool you with seasonal businesses, where the fourth quarter is supposed to be much bigger than the third.
Use QoQ for businesses that are not strongly seasonal, or when you want to see the latest trend without waiting out the 12-month lag of the year-over-year view.