To say that Eric owes major plot points to Faust would be to assume that Terry Pratchett didn't get the joke...and we know the man gets the joke, he writes the jokes. The front cover of the book is the first give away, the title is actually Faust (which is crossed out), then Eric. So, we know going in that there is going to be a deal with the devil in return for something. And there is. Eric is a young boy (I think he was twelve) who tries to summon a demon so he can have three (or more) wishes fulfilled. Something about ruling the world, the most beautiful woman in the world...and...well, I forget. He thinks he is summoning a demon. What he gets is Rincewind, a fairly incompetent wizard who has been the focus of a handful of prior Discworld novels. Since Rincewind can't really do anything right and he is trailed by some walking nearly sentient luggage which will attack anything that poses a threat to Rincewind, much to the dismay of Rincewind, Eric's wishes do not exactly go as planned. We are taken to the beginning of time, hell, to the events of Iliad, and more.
Rincewind is perhaps my least favorite protagonist in all the Disc, though I'm a big fan of the Luggage. Somehow in this shorter Discworld novel I didn't mind Rincewind. The pace was fast and it was funnier than many of the previous novels. I know this is a humorous fantasy series, but I can't say there are any laugh out loud moments. Hilarity doesn't exactly ensue. But good humor does ensue. That's a plus.
Pratchett writes situations that are funny or humor filled (having Helen of Troy being a middle aged mother of five by the time she is rescued = humor filled; the Universe beginning with a Paper Clip rather than a Bang = funny), so it is a breeze to read.
This ninth Discworld novel was one of my better experiences on the Disc.