The filter has been removed in ACF5 and was not replaced. Instead there are function to call depending on what you need.
get_fields() returns all the values for a specific post. http://www.advancedcustomfields.com/resources/get_fields/
I’m not sure there’s a function that gets all the field values based on the group id. There is a function that gets all the field objects by the group id. ‘acf_get_fields($group_key)`, this one is not in the documentation.
