I purchased my chi over a year and a half ago and it still works just as well as it did when i first used it. I have thick, wavy hair and it takes me about 10-15 minutes to make my hair straight. Which is super, cause who has the time to stand around in the bathroom all day trying to achieve perfectly straight hair? Make sure to use a heat protector on your hair before using the Chi, or any other heat styling product for that matter.
You are also supposed to be able to use it like a curling iron, and I've actually seen people do this, but I have had no personal luck with this technique.