A Cavern of Black Ice is a huge 769 page long book, but only the beginning of a story that happens in a fictional realm of feudalism and magic. You just have to have the classic hero journey, starting with a young man torn from the world he knew and was comfortable to him, partially mentored by a wise and hitherto unknown relative, given a reason to trek on a perilous journey and beset by powerful, yet strangely ineffectual enemies. Of course, Deus ex Machina abilities that help him and his quarry escape tight situations are also there.
But there is more: various clans living in a cold inhospitable North, the ambitious ruler of a city coveting the resources of said clans, a mysterious and powerful entity chained by the ruler, a strange and magical race of people even further north, a secret sorcerous society, female assassins that you can't quite remember what they look like, a dark realm where dangerous creatures await release and so on and so on.
The thing to understand here is that J. V. Jones set to create a vast universe in which multiple interests clash to create a captivating story. The writing is good, the characters are decent, but there is something missing and while I can't quite put my finger on it, I suspect it involves editing. There is too much text for what the story wants to say and when characterisation is concerned, some actions or even complete characters are just pulled out of a hat. And remember, this is just one of at least four books in the Sword of Shadows series and it barely scratched the surface of it all.
Bottom line: I liked the book, but not so much as to be absolutely certain I will continue to read the rest of the series. When I finished reading it I felt actual relief. If you want to spend some time immersed in a fantastic fantasy universe, this might be a good fit for you.