Instruct: Classify the given Amazon review into its appropriate rating category
Query: Not the most effective for very thick hair.

It's easy to use but didn't get my hair as smooth and as straight as I'd hoped. I also didn't realize that your hair has to be 100% dry to use it. I was hoping this would keep from having to use a blow dryer and a flat iron. Would probably work well for someone who doesn't have very thick, course, curly hair.