I'm currently building my own task list in WDJ. I have found the BPM api to be very limiting.
A simple thing like displaying the process initiator User is not possible. In the base "private" api, this is available. Unfortunately if has not been made available in the public facade.
I was wondering if there is a way to get to this user. I have added my initiator user to my task context and get around this issue in that way.
I just hope that SAP would be enhancing the BPM api soon!