Ah Content Types, the root of any good Content Management System. Many a user has asked me “why do we need multiple Content Types?” It is a good question in that SharePoint 2010 has powerful full text searching (the ability to search on the contents of a piece of content). The first four things that come to mind, in no particular order, when I think of content types are Metadata, Search, Navigation and Views.
Metadata
Metadata, data about the data, can not only provide enhance search functionality, it can provide powerful navigation, as well. Metadata may contain information that is within the contents of the content or could be data that provides further descriptions or references to the content.
Search
The ability to categorize content into different buckets, as well as, associate diverse sets of metadata to each Content Type can make search even more robust. Say I wanted to find all the invoices that were produced between a certain date ranges, by a certain person, for a particular company. We could find this document utilizing full text search if all the required information was contained within the content of the document. Most likely it isn’t. This is where that handy metadata comes in.
Navigation
In SharePoint 2010, there is a powerful tool called Metadata Navigation. When the metadata is defined appropriately, Metadata Navigation can replace even the most complex outdated and inflexible folder structures. The key to success in implementing Metadata Navigation is to have navigational flow in mind up front when creating your metadata for each unique content type.
Views
Content types and they associated metadata are key to being to create useful customized view, in SharePoint. Some of the main features of views in SharePoint are the ability to sort, group, and filter to create customized views based upon your metadata associated with your content types.
In the next few weeks, I will go into each of these areas further and provide some relevant screenshot examples. If you have any questions feel free to comment or contact me at rob@sharepointholmes.com or on twitter at @drholmesnj.
SharePoint Holmes 
Great overview. Additionally one gets:
– Centralized management that can span content databases (via the Content Syndication Hub)
– Information Policy (for document disposition)
– Workflow; although this requires Globally Reusable or custom workflows
What I’d like to see added to Content Types are:
– Views
– Security restrictions