well designed,easy to use,excellent documentation,but …

This is a very high quality plugin. It is easy to understand and easy to use. The layout is very logical and efficient. The documentation is excellent. The quality of this product easily equals that of commercial products. ACF works really well. However there are some weak points. It is not a comprehensive CMS solution so you will need another plugin to do custom post types and custom taxonomies. I used “Custom Post Types UI” and it works well with this plugin. A more critical deficiency for me is ACF does not support multi-valued (repeated) fields or group of fields. (This feature is apparently available as a premium feature but not in the freeware version.) For me the lack of repeated fields or group of fields is critical and I have decided instead to use Magic Fields which has this feature. But Magic Fields is inferior to ACF with respect to quality, documentation and support.