Well, I've been pleasurably wading through this slab of witty exposition for what feels like most of the year now, re-reading it, to be exact, and finding comfort in the chaos, warfare, catastrophe and upheaval of the late 1600s. Daniel Waterhouse wends his way back to England beset by pirates and recalls his formative years attending Cambridge with a young Isaac Newton. Raised by a religious extremist who believed the world would end in 1666 (obviously) and wanted Daniel to stand on the Cliffs of Dover ready to great the returned Jesus in a variety of ancient languages, Daniel's education begins as a great revolution in science and philosophy takes hold, shaking the world to its core simply by explaining it. Then we have Half-Cocked Jack Shaftoe, who rescues Eliza from a seraglio at the Siege Of Vienna. Together they cross Europe as Vagabonds, ready to take the world of finance by storm.
These books aren't everybody's cup of tea: too big, bloated and clever-clever. I love 'em. I eat 'em up. They're epic, picaresque, hilarious celebrations of wild intelligence at war with crazed irrationality, and you're not always sure which of them are the good guys at any given time.

Found my original review from 2004:

This vast, sprawling historical (actually an alternative history) novel is the first in a vast, sprawling historical trilogy that ambitiously sets out to chart the rise of the age of reason and enlightenment, which, it must be noted, marks no abatement in man’s eternal quest for new and interesting way to kills each other, but which certainly saw a marked increase in the numbers of obsessive scientists suffering from mercury poisoning. 
1713, the story opens in the Colonies and the arrival of Enoch Root, Stephenson’s more sanguine immortal Melmoth figure (who also figures in Cryptonomicon, to which this trilogy is a prelude) searching for the now aged Daniel Waterhouse and prevailing upon him to return to England to mediate in a bitter, wildfire scientific feud that has riven the ranks of the Philosophical Society which Daniel helped found. Old Daniel then spends the rest of the nine hundred-odd pages on a ship trying to leave Boston Harbour. Unfortunately the ship is beset by a large fleet of pirates and is captained by a man with a real hard-on for buccaneers and whose idea of a good time is to send as many of them as possible to a watery grave. Lively and all as the ensuing maritime manoeuvres prove to be, the bulk of the actual book is thankfully filled with the tale of Daniel’s early career in the Philosophical Society and his friendships with various historical characters, most significantly one Isaac Newton. Against the backdrop of plague, fire, revolution and restoration, we are treated to debates, feuds, intrigues, dissections, theories, revelations and the whole cloistered, obsessive world of mad, venerable old scientists who can’t blow their nose without making new and awesome discoveries and then writing treatises of thousands of closely reasoned pages on the issue, and others who blunder down disastrous dead ends ruining their lives, fortunes and reputations.
Book One ends, and Old Daniel is finally making progress for England. But never mind about him, Book Two brings us the exciting adventures of the legendary Jack Shaftoe, King of the Vagabonds, and Eliza, rescued from a Turkish harem at the Siege of Venice. The two set out to make their fortune in the markets, courts and battlefields of war-torn Europe. ‘Half-Cocked’ Jack is slowly going mad from a fatal dose of the pox while Eliza has a gift for numbers, intrigue and networks which gets both of them into horrible amounts of trouble. Swashbucklingly stupid exploits and fiendishly clever stratagems which flounder and backfire keep the second book a lively read, and we even get to revisit young Daniel – well… getting on for middle-aged Daniel - in filthy, teeming bristling London.
Personally, I love this sort of thing, and I’m also a fan of Stephenson anyway, so Quicksilver was never going to be a hard sell to this particular reviewer. The giddy sense of scientific discovery fuelling the progress of civilisation, for better and for worse, is all part of the pure bliss of science fiction, and the counterpart in historical fiction can be every bit as exhilarating. The work of the Philosophical Society does not occur in a vacuum, cannot be divorced from the cultural, political, religious and economic milieu in which it is set, which enables it far more than it hampers. The scientists are not innocently unaware of the personal dangers of questioning widely held beliefs of the nature of the universe, nor are they ignorant of the admittedly unpredictable, potentially catastrophic repercussions on the wider world (or, in the case of their work on cannon and gunpowder, very predictable) it is simply the nature of the world in which they live. 
Tons of historical detail abound, but Stephenson makes no effort to capture much in the way of period dialect or idiom, though he does well in capturing the rhetorical rhythms of courtiers and Natural Philosophers. The ferment of scientific endeavour and extremes of thought and behaviour in the Philosophical Society allow for a great deal of high and low comedy, while unashamedly vicious behaviour can shock and the uncertainties of life in such tumultuous times leads to much tragedy and horror. One passage consists of an hilarious description of the outrageously flamboyant dress of a foppish young aristocrat, a patron of Isaac Newton and a deadly swordsman. In the very next paragraph amusement gives way to revulsion as the same fop horribly abuses an agent in his pay.
Ending with all the principal characters in assorted unpleasant if not downright disgusting circumstances and with two equally massive books to go, it’s clear Stephenson is just getting started. Reading the whole lot looks like as potentially exhausting experience: heck just lifting the damn things could leave you prostrate, but me, I’m a glutton for punishment.