In many ways this really isn't a good book. The style borders on choppy and dense. The story doesn't always flow. MacDonald routinely makes excurses without telling you. But...
The "mythopoeic" prose is its redeeming quality. MaDonald bathed the book in sacramentality. Every leaf, grove, and spring refleted redemption--and MacDonald is a talented enough artist that he can show redemption without telling you redemption (usually).
The story line is simple enough. The protagonists finds himself in "faerie land" and must navigate through trials and temptations, with all the self-discoveries.
CS Lewis mentioned this book spoke of a "good death." Seems odd that a Christian (even a heterodox one) like MacDonald would be so preoccupied with Death when most of MacDonald's works ooze "Life." What Lewis means is that MacDonald uses the medium of "death" to kill the old element and make way for the new (Life). This is none other than the Christian story of Baptism, a Baptism that our hero must undergo.
Some things I learned about Fairie Land:
*Fairy wisdom is sounder than anything we moderns have come up with.
*The Arthurian legends are reliable guides to the human conditions and are "true" on more than one level.
*Giants prefer to use maces in battle.
*Adventures usually happen in Forests.
Sometimes the beauty was so intoxicating that I felt my heart would stop. Accepting what I now do about Plato and Carl Jung, MacDonald plucked an archetypal chord in my soul.