It's 5400RPM, it's the same speed as the hard drives currently in Macbooks. Also, with increased platter density, you gain a modicum of speed over smaller drives with the same rotational speed. Sure, 7200RPM is significantly faster, but you don't have 500GB as an option at that speed, not to mention the fact that you have to deal with increased heat and a decrease in battery power as a result of the extra speed.