Will the Royale Straightener work for me? Reviews perhaps?

Okay so I have a problem. I have curly hair that I barely ever straighten because it doesn't stay straight. I went to the mall the other day and the people at the Royale Straightener kiosk straightened like part of my hair and so it sorta stayed straighter, but it was hard to tell. I hear it is AMAZING & it has a five year warranty and everything, but I also hear if you buy it from the kiosk the warranty won't be like validated or something? Anyways I have a Chi now it works soo-soo about keeping it actually STRAIGHT.