It's not the best way to work your abs. You really don't need a device to work your abs effectively. And if you were to sue a device the ones I would recommend are a decline bench to do decline situps on or a swiss ball.
Sit-ups and crunches work the abs well, but they aren't gimmicky so they don't get much aattention. Decline sit-ups, hanging leg raises, wraparounds, bicycles and planks also work well.
