Instruct: Classify a given Amazon review into positive or negative sentiment.
Query: Top Notch !

I used this product for 3 months and like someone said, noticed the biggest improvement in my hair. It was stronger and shinier, even through stress and highlights. My nails did improve greatly, but when your friends and (especially your hairdresser) want to know what you are using and how to get it, you know it works. I tried regular biotin supplements, but they did not do as well for me. The only caution is that if you stop using it, the benefits do eventually diminish and it says that up front on the package.