Useless, absolutely useless.
Facebook is primarily used for people to socialise on - not to find products or services. Yes, people do recommend sites or pages but, only amongst their friends - no use to a business wanting to promote their service or products is it.
I know that Social Media is now the big "in thing" and, a lot of businesses/services do have a Facebook page but, AND THIS IS A BIG BUT, they have a website as well. Facebook is used primarily to update people not to advertise a business/service and, is only useful if EXISTING customers have liked or subscribed to the page.
Think about it, you want your garden landscaping - where do you go to find a company - Facebook? No, didn't think so. So, why do people make the big mistake of only having a Facebook page for their products or services.
Neither of my two business, either Typing Solutions or, Typing from Home have a Facebook page. To have a Facebook page you need to be updating regularly with new promotions, etc, and have a lot of people subscribed to it.
I have a Facebook "recommend" button on the Typing from Home Website and, that is slightly different. If a satisfied visitor likes the site and what they have read, they can hit the Facebook recommend button. This would then show up on their Facebook page as, "So and so recommends Typing from Home" with a nice little picture of my book and a link TO THIS SITE not some bland Facebook page.
Personally, Facebook for me is where I go to see what my friends are up to not to advertise my Typing Service or, to sell any of my books.
So, I will say again, if your business is languishing, you are not making any sales, obtaining any clients and you don't have a website, make one now. Not just that, ensure your website is well optimised and will be ranked highly in all the search engines. Just like this site which is No 1 one Google UK and Google.com.
If you already have a website and, it is not performing well, it will be because you do not have the right pages and, it is not optimised correctly.
The book "Create a high ranking website - the Foolproof way" details step by step how you create a high ranking website, easily and simply. It is written in non-technical language and contains information on domain names, page titles, meta tags, website builders and, all the behind the scenes work required to make a website a high ranking, high performing website that will be attracting the sales and clients that you need.
Also, check out this article on Website versus Facebook Page