This is a masterpiece.  Five stars is not enough.
 
(BTW, I HATE SPOILERS, so you will NOT find any here.)
 
Forget everything you think you know about how a novel should be written.  Ms. Clarke makes her own rules and the result is astounding.  I think it is best to approach Jonathan Strange & Mr. Norrell without any expectations, and to surrender and be led on its sublime odyssey.

In this brilliantly written epic literary historical fantasy (I suppose that is its sub- sub- sub-genre), we are transported to the early 19th century where we meet some very engaging magicians and follow them on their paths, and we explore English magic and its history.‎

I was swept away by the style in which this is written, which is very much like a British classic,‎ so it flawlessly captures the time in which it takes place.  The prose is magnificent - Ms. Clarke sculpts the language to create a beautiful work of art, with incredible intricacy. 
 
I think the story is phenomenal - the reader has no idea where it may take him/her, and I was delighted with every twist, every turn.  It starts slowly, and‎ the story line builds, ever so gradually, but steadily and teasingly, progressing toward a crescendo - all at a slow pace that's almost maddening, but it's such a tantalizing and exciting experience that I didn't want it to end.  It gives the reader (me, anyway) the sense that something tremendous will happen.  And of course, it does.  
 
I adore the characters, all of whom are brilliantly crafted and every one of them jumps off the page.  I found each of them fascinating and memorable, some venturing into "favorite characters" territory.
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‎Ms. Clarke deftly blends ‎historical figures and events, English folklore, a fascinating background of magic, and amazing characters to form an alternate history that is seamless, richly detailed and uniquely hers. A‎nd she makes it believable.‎
 
There is more elaborate detail in this book than I have probably ever seen, well, anywhere, making the world-building pretty much incomparable.  Copious footnotes educate us about this alternate history and its events, figures and countless other things of interest with magnificent detail.‎
 
It's also hilarious.  The dry and often dark humor fitting naturally into the already fantastic story makes this book soar into the realm of the finest works I've ever read.  It made me laugh out loud, chuckle to myself, and probably sit there with a dorky grin on my face through a lot of scenes.
 
The magic is dazzling and creative, and each spell seems to brilliantly reflect the personality of the person casting it. It's perfect.‎

The story does move slowly, and it took me a little while to really get absorbed - I think I needed to get used to it and adjust myself accordingly.  But once I did, I grew more enthralled with every page.

I knew by about halfway through that this book would be heading to my favorites list, regardless of how it‎ may have ended.  I'm confident it will remain there forever, and that it will be a book I want to reread countless times.

So, Ms. Clarke, about that sequel...‎ :)
 
People seem to either love this book or hate it.  I'd highly recommend it if:
 
- You enjoy reading classics, particularly British ones (or don't mind their style) (otherwise the style might lose you‎)
- You appreciate dry humor (and dark humor)‎ (if you don't see the humor, it will lose a tremendous amount of its charm, maybe most of it)
- You like fantasy, but you're not looking for a fast-paced, action-packed, Hollywood blockbuster-type of book‎ (it's not)
- You don't mind a slow-paced story with an immense amount of detail and you don't mind taking your time with‎ it (this is essential)

It will also help if:
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‎- You appreciate prose and enjoy colorful use of language‎ (that made me savor it)
- You appreciate world building‎ (the amount of detail may otherwise annoy you)
 
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I can't say enough good things about this book. I'm not exaggerating when I say it's one of the best I've ever read.‎