If you share my usual distaste for aliens and can't put it on hold, you should skip this. Otherwise, dive in.
The formula is the same as Dan Simmon's SF award-magnet "Hyperion (Gollancz S.F.)
", but "Downward to the Earth" came first and is superior in my opinion. It's a quest through a wondrous alien landscape, based somewhat on a classic (Conrad's "Heart of Darkness
"); the aim of the quest is some kind of transcendental atonement; the journey and its recollections provide back story, colour and mystery.
The jungle world that the hero travels through is intoxicating, strange and sensual, and while everything that occurs on it is ludicrous, it all somehow works. I found myself drawn in by the dreamlike, druggy unreality of this book and, in that hazy context, could believe in the character's compulsion to see the elephantine natives participate in their "rebirthing" ceremony, his fear to take part in it himself, his resolution to do so regardless. I wasn't even put off by realising early on what the nature of this mystery was likely to be, as I'm sure that Silverberg expects us to guess what the hero is in for before the hero sees it himself. There is no anticlimax, only inevitability; we still share our man's triumph when he completes his quest to become both a true expression of himself and something more than human.