Sentiment has been designed for any business that physically interacts with more than a handful of customers every day.
If you have any dealings with customers who you do not intimately know then you can benefit from Sentiment. It might seem like there's not much you can learn from just a simple button click but knowing what the silent majority of your customers really think - as opposed to what you think they think - is eye-opening.
Because of this Sentiment works great for businesses such as any retail, restaurants, hotels, spa's hairdressers. But because it can be used on a phone it also gives great insight for more mobile businesses such as coaches, taxi's, plumbers, and those attending trade fairs and markets.
In short if you are not getting the feedback you need it will be a benefit to your business.