The Key To Time was a good storyline but then nobody liked the idea of a season long stor arc at least they had the benefit of two those stories being written by Robert Holmes. But on the new show River's story arc was stretched out over four years, she'd be a hard character for a newbie to understand at least to me.
Eh, how do you explain The Master, who has a much, much longer Arc? Or Time Lords and Gallifrey? Or the Evolution of the Daleks. There's a rich history throughout, that could be summed up in a sentence or two, or could be discussed for an hour
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?