I mostly liked it, especially Rose's bit at the end. Go Rose! However, it has the big flaw that all of these types of stories have. If the guys who imprisoned him set up such elaborate mechanisms to throw the planet into the black hole if it ever looked like he was going to get free... why the He!! didn't they just throw him in it in the first place?! (And I do NOT want to hear: "Because then they wouldn't have a story.") Obviously, they were moral cowards who wanted someone else to do the dirty work for them. (There, saved you the trouble of answering.)
And why was the Doctor going on about the impossibility of the 'before time' concept? If the Big Bang theory is correct there's no reason to assume that there wasn't something going on before it. Some scientists even think it might be a (looooong) cyclical event.