Forget about the fact that this is written as a fantasy novel. It could as easily have been written as SF novel about time travel. The use of "magic" in the plot requires no more suspension of disbelief than does the existence of advanced alien technology - like time travel machines.
The plot just gallops along, a new twist and turn on every page. The characters are vividly drawn. The setting is early 19th century London, and the literary world inhabited by Byron, Keats and Shelley. Tim Powers writes it like the bastard son of Charles Dickens and William Gibson. You won't be just reading about this world; you will be in it.
The plot - what is really happening - is revealed to the reader at same rate as to the protagonist. You will find yourself forming the connections at the same rate as he does. Almost every second page there is another reveal - a moment where you go "Aha!, so that's what is really happening". Its almost impossible to put down (I read it in one sitting), it sucks you in big time.
And at the end, every single loose end is tied up. You look at it in retrospect, and it is like a Swiss watch movement. Every character and every plot turn is connected and serves a purpose. You will want to read it again straight away just to appreciate how cleverly written it is.
One piece of advice, particularly to those new to Tim Powers. Don't be put off by the prologue. Its all swords and magic, you won't have any idea of what is going on, and its very unrepresentative of the book as a whole. The first chapter will take you back into the real world of airplane travel, and academia, and literary conferences, and slowly and almost subtlety draw you into a very different world. The prologue exists for a purpose, but only at the end of the book will you understand how it fits in and why it was necessary. Don't be put off by it.
Buy this book. Start reading this book. Just don't plan on doing anything else for the next 8 hours. You will trapped in 19th century London until Tim Powers decides its OK for you leave. This book is a work of genius.