The course was pretty fun, not too difficult. A lot of readings, but as long as you keep up you should be fine. You go through a lot of stories so reading isn't as much of a chore as it would be for say history. They have a nice narrative to them that keeps you interested. To be honest, you could get away with reading wiki's and summaries on the myths but would miss some of the details from the actual sources.
Obviously things will change with the prof, but I had Graeme Ward last year and he was a pretty good prof. Lectures were always interesting and he had a good style of lecturing. Tests and such were also not too difficult assuming you did the readings. Here's the mark breakdown we had:
Reading Quizzes 10%
Test 1 25%
Test 2 25%
Final Exam 40%
Reading quizes were short pop-quizes he held randomly throughout the term. It was something like five questions you could answer in one word. There weren't too many, so an easy 10% depending on how you approach it.
Here's the books we used as well to give you an idea of the myths you might encounter. Just remember this could change so do go out and buy these expecting to use them:
The Complete Aeschylus Volume I: The Oresteia, P. Burrian & A. Shapiro, eds. (2011)
Euripides, Four Plays: Medea, Hippolytus, Heracles, Bacchae, S. Esposito, ed. (2004)
The Works of Hesiod and the Homeric Hymns, D. Hine, ed. (2005)
Homer, Iliad, R. ***les, trans. (1991)
Ovid, Metamorphoses, C. Martin, trans. (2005)
Vergil, Aeneid, R. ***les, trans. (2008)
Hope this helps.