It's a quick and efficient way to get your site online. If you have limited time, then a website builder is definitely the way to go. As a website builder, Shopify is pretty basic in terms of design. A beginner won't be able to create a unique or dazzling website on Shopify, at least not without the help of a developer.
In addition, having a real, dedicated site makes a company seem more authoritative and trustworthy than a Facebook or Tumblr presence on its own (although you should also consider those services as elements of your online presence). If you don't think it's worth investing in a web designer, or you think you're not ready for it, you still have plenty of options. I conclude that it's worth testing your team with recommendations to others who may be interested. Those companies also offer e-commerce websites, which might be worth checking out if you're worried that Shopify won't let you build the site you want.
Another reason worth considering, both for personal and business purposes, is that creating your own site gives you endless design options.