There are a lot of bugs. Missspellings mostly. And the major problem with the plugin is, that it´s fixed like hell. the output of the attendees is in a table and the event-registration.-form misses unique IDs. (every element is named "help"...?). so you can´t disable parts/fields of the form, bceause of:
*) lack of unique css-ids
*) no admin-panel to deactivate the unneeded parts the php is requesting
every try to rework the plugin ends in an error... or a complete rework and a new plugin for which i simply don´t have the time.