The 2010 cruise control differs from the 2005 cruise control. The good news is that it remembers it's setting even when you come to a complete stop and resumes once you are above about 25 mph. The bad news is that, in the ECO mode at least, it maintains the set speed +/- about 3 mph on roads with small hills.
When the 2010 cruise is set the lever behaves just like the gas pedal. Hold it up and it accelerates constantly. Hold it down and it starts charging the traction battery to reduce speed more quickly. Moving up or down, you have to lead it a bit to arrive at the desired speed. For example, if you are at 45 and hold the lever up until you reach 55, releasing the lever at that speed, you will end up cruising at 57 or 58.