Hi Elmagnifico,
I thought i had set this support forum to notify me of new threads, which i was wrong. so sorry for the delay in getting back!
Depending on the file that you upload the importer should choose what type of import to perform automatically. (so if you upload an xml file you will be show settings and fields that are xml specific, the same for if you were to import a csv file. If by anychance the importer gets the file type wrong you can manually set this on the importer data map screen.
By "popular wordpress importer" are you meaning the default wordpress importer that imports (previously exported wordpress xml files) into wordpress?
if so then JC Importer can import these files but is really meant for importing custom xml files that can be mapped to post_types, taxonomies, or users to give you flexibility in what you want to import.
As for complexity of import all you need to do to map xml files in jc importer is choose the base node which sets what xml is treated as a single record and then set each field that you want to import to a part of the xml record.
Hopes this helps
James
