How do I know if SEO is worth it?

Although SEO is fairly time consuming, the best way I’ve found to think about it as being a worthwhile use of time is that it is free-advertising to a degree.  The more well known your company becomes, the more business you get, and with the more business you get the more positive reviews you can receive.  This create a circular pattern; with more positive reviews the more people will find your results in search engines and want to use your services and/or products.