I really enjoyed it. A good, ol' fashioned space opera and definitely one of Terrance Dicks's best. If Doctor Who had come back to screens during that period, it would have likely coasted on the waves of stories like Shakedown (probably as a six-part story). It's a great deal of fun. That said, I'd look at the price of the paperback first. Read/listen to the first couple pages with the previews and see which you'd feel more comfortable with. It's worth having either way.
"Courage isn't a matter of not being frightened you know; It's being afraid and doing what you have to do anyway."