It's probably the most potent plugin I've used with WordPress. It almost made me feel a real developer :)
The ability to relate custom post types directly from the UI is awesome and lets you create many distinct uses for your sites. One-to-many and many-to-many relationships will give you alot to work on.
The UI and workflow could use a little polish but, nevertheless, it saves you a lot of time and enables non-coders to achieve great results.
I think the closest I found to this plugin was Pods, but Pods uses it's own nomenclature, and it got me confused with new terms (Pods calls content types to custom post types, custom fields and custom taxonomies, which they are, but new terms are dispensable even if the WordPress original terms are bad).