Wordpress.com is a really great way to get your website up in an instant and with minimum expense, allowing you to put your mind to developing your content. Wordpress.com uses a standard installation of Wordpress, but does not allow you to install plugins or do much theme customisation. By keeping things simple you'll never have to worry about your website staying live, performing quickly or staying secure. And if you do find it limiting, its easy to switch over to a self-hosted installation of Wordpress.
Here is an example of how we've put Wordpress.com to use to create a fully functional campaign site: