This ‘free plus shipping’ type approach has been empirically proven in a variety Psychology of Marketing studies and has been recently popularized by researchers such as Dr. Dan Ariely, the James B. Duke Professor of Psychology and Behavioral Economics at Duke University and author of the hugely influential book Predictably Irrational. We’ve seen this approach drive increases in sales of an upsell product 3-4-fold.
While the the best of them offer surprising amounts of flexibility, they also impose stringent enough restrictions to page design that you shouldn't be able to create a really bad looking site using one of these services. Typically you can get a Mysite.servicename.com style-url with no commerce abilities for free from one of these services; you have to pay extra for a better URL and the ability to sell. One issue to consider is that if you eventually outgrow one of these services, it can be hard to export your site to a full scale advanced web hosting like Dreamhost or Hostgator. If you know that's where you are eventually going, it may be better to skip the sitebuilder step.
One downside of most of these services is that, should you someday want to move to another web host, you'll likely be out of luck because of the custom code they use to display your site. Only a few of the services here let you take your site to another web hosting service: The most complete example of this is Weebly, which lets you download the standard site server folders. Squarespace offers some transferability by letting you output your site in standard WordPress format. As you might expect, the same transferability holds for WordPress.com.
You need to understand your audience like you do your very own yourself. You are aware of your dislikes and likes, you know what problems you face and you know the sort of people you will let help with those problems. If you learn to know your audience in the same manner, the chances of you establishing a genuine connection increase vastly. You will also be able to guide more people through your sales funnel and get those coveted ‘closed-wons’.