As Martin wrote,

"The best slomo results that I've achieved (using the Z1 and Apple Shake) have been when the shutter speed was adjusted for the intended playback speed of the video. In other words, the actual shutter speed at the time of recording divided by the speed factor (e.g., 0.5 for half the speed) should be 1/60, such that the amount of motion blur visible at playback time is the same as what an appropriately overcranked camera would have recorded. Then the amount of blur looks right for the playback speed."

What kind of slow motion look is this process achieving?

"the actual shutter speed at the time of recording divided by the speed factor (e.g., 0.5 for half the speed) should be 1/60"

Can someone explain this a little more?

Thanks. Paolo.