I just tried the new Business class from TXL-LPA. It is the same model as Iberia Express and KLM. but I think airberlin could improve the service but given more space in between the seats, have a dedicate menu for the business class, have a bathroom only for business class and a curtain to separate the cabins.
one thing I did not like was the flight crew did not welcome on board the platinum members which is a normal practice on business long haul flights.
Overall the product can not be compare with excellent business long haul product