WordPress has a templating system, which includes widgets that can be rearranged without editing PHP or HTML code, as well as themes that can be installed and switched between. The PHP and HTML code in themes can also be edited for more advanced customizations. WordPress also features integrated link management; a search engine-friendly, clean permalink structure; the ability to assign nested, multiple categories to articles; multiple author capability; and support for tagging of posts and articles. WordPress also supports the Trackback and Pingback standards for displaying links to other sites that have themselves linked to a post or article. Finally, WordPress has a rich plugin architecture which allows users and developers to extend its functionality beyond the features that come as part of the base install.
Multi Blogging With WordPress
WordPress supports one weblog per installation, though multiple concurrent copies may be run from different directories if configured to use separate database tables.
WordPress Multi-User (WordPress MU, a.k.a. WPMU) is a fork of WordPress created to allow simultaneous blogs to exist within one installation. WordPress MU makes it possible for anyone with a website to host their own blogging community, control, and moderate all the blogs from a single dashboard. WordPress MU adds eight new data tables for each blog.
WordPress Installation Requirements
You need to ensure that your hosting package does have one new MSSQL database available for the installation. Without the accessibility of the MSSQL database, the free installation will not work and hence, your WordPress cannot be installed. It requires Windows 2003 hosting with IIS 6 hosting compatible, Windows 2008 hosting with IIS 7.0 hosting compatible in ASP.NET web hosting plans.
1) You gain full control of the modules, pages and design of your blogs.
2) Categorize your blog posts in more easier ways
3) Add more fun and flexibility for your blogs by upgrade of installing themes and plugins easily.
1) Not Free. (Apply to the cost of your domain name and web hosting account)
Which one is right for you?
There is no absolute answers for this questions. It is depends on your mission and vision of creating your blogs. Free blog hosting WordPress.com are ideal for normal blog users to post their view or comments on particular topics where else self hosted WordPress blogs are ideal for users who are planning for long term blogging for more value creation or business based blogs.