As in any business, you need to do some research and have some sort of business plan before you start committing yourself to contracts and debts, even if only debts of time and emotion. While there is no guarantee that any new business will succeed, according to the small business administration you have a better chance of success if you have done research and have a business plan BEFORE you become involved in your new endeavor.

The single largest disadvantage in most peoples' eyes will be the ads that clutter their site or pop-up when the site is visited or the visitor departs. Not only does this tend to obscure YOUR message from your visitors' eyes, but it may also cut short the time they spend on your site. They go elsewhere to a more professional looking site, or they follow one of the web host's advertisements...which was the reason you got the site free.