Using the standard content as well as additional fields, you are able to apply standard content plugins as well as special FC plugins - and combine them as you like - truly flexible.
Additional benefit: Code adjustments - if necessary at all - turn out as tiny patches, applicable without too much knowledge.
Equipped with tons of features and a very user friendly interface, FC is a must for all my projects.
Still you can say that FC still has a lack of documentation. On the other hand it is so easy to handle that you probably will spend only little more time with learning by doing (which you have to do anyway, right?) than with an exhaustive documentation.
In my case, it took me about one hour to understand enough to get started. (If this is your first CCK, maybe take two…). Well invested time - life gets so much easier afterwards.
The very active developer and forum will help you quickly with all the rest.
In Summary: Top edge - more than five stars.