The key good points in this story for me were that it left many unfinished threads to be revisited - who set up the advertisement and interviews, who appears to be one step ahead of the doctor - that we have to wait to find out.
In the meantime, there is almost a distraction in this tale of the Doctor apparently looking for a 'new apprentice'. I'm not a fan of The Apprentice so I didn't enjoy this story quite as much as others have; but that doesn't detract from the good writing or the excellent performances from the characters; many of whom have pivotal roles to play in what must have been quite difficult characters to portray convincingly in such a short space of time. The casting is brilliant; and the setups for future stories is great; just this story seemed to have a little of the 'filler' in it for it to be what I would consider a fantastic Doctor Who story.
Well worth listening to; and the extras and interviews are very interesting as well.