Alan Dean Foster wrote a nifty little novel entitled Sentenced to Prism, where he explores a crystalline world with prismatic lifeforms. His vision and detail were excellent. He applies this talent again in Voyage to the City of the Dead where the planet of Tslamaina is composed of one circular ocean which is surrounded by kilometer-high cliffs of earth. Along the gigantic river of Skar, there are villages dotting the delta and riverside areas. The three intelligent native species live among the different climates of the river, which runs all the way to the north where a massive icecap feeds the flow. And like in Sentenced to Prism, Dean Alan Foster fully explores the facets of the gem of a planet.
The human exploration of Tslamaina is being conducted by a husband-wife geologist-anthropologist duo. Their sophisticated hydrofoil is the most advanced object on the planet and an object of desire for some of the conniving locals. Though bickering much of the time, each one devotes their time to studying their own subject... which bores their partner to no end is becomes the source of schism. This chasm of understanding between the husband-wife team only grows larger as they move further up the river and it also becomes the divide where you begin to dislike the novel because of the petty bickering.
The voyage is full of exploration of the geography, discoveries of geological interest, probing of the values of two of the local intelligences, exposing the coping of life between the social divides... it's all quite well done and maintains a great pace of discovery. The last 20% of the novel pulls a four punches: one disappointingly anthropomorphic trait rears its head, one kind of obvious destination conclusion, one WTF left-field addition, and one neat idea which ties in with the WTF.
Ultimately, while the discovery aspect of of great interest, the nagging couple drag the reader away from the meat of the book and the ending is something which is just completely unsatisfactory. So, come for the xeno-sociological bonanza and simply be wowed by it, but don't expect anything fancier.