Cryptonomicon is Neal Stephenson's technothriller about cryptography and is a precursor to his baroque cycle. Like many of Stephenson's novels it uses multiple points of view to tell the story weaving them together into a single narrative, or in this case two narratives from the 1940s and 1990s.Stephenson does manage to keep the narrative moving despite the frequent changes of focus by interrelating the sections and leaving cliff-hangers on each narrative fragment.
For any reader who has read the Baroque trilogy there are many familiar family names for the characters, with a number of famous historical figures making cameo appearances including Alan Turing and General Douglas MacArthur.
One common feature for Cryptonomicon with many other technothrillers, even those written byTom Clancy who I'd not particularly associate with Stephenson, is the frequent infodumps. These are less common than in the later Baroque Cycle and do not detract too greatly from the flow of the novel, helped by Stephenson's humour and attempt to make them appropriate in context.
Cryptonomicon is an exciting read though as an alternative history does not have the levels of invention that characterised Stephenson's earlier work like the The Diamond Age or Snow Crash. It can clearly be seen as a transitional work between his briefer earlier SF work and the lengthy alternative history series of the Baroque Cycle.