I enjoy this book for the same reason I enjoy the Leatherbound Special edition Player's Handbook and Dungeon Master's Guide.
At risk of repeating myself, If you love the look and feel of a leather book, as I do, then you will love this book. It is true there is nothing new but the errata (which is available online anyway) but then this means this book is one you buy purely by choice, a choice any book lover would be happy to make.
It is durable, like its two predecessors, able to take the beating gaming books inevitably suffer when carried around in book bags to far off gaming tables to game. I have used my leatherbound PHB and DMG in many a mobile session now and they look and feel in as good condition as when they were new, with none of the scuffle marks one gets on the regular plastic-laminated hardcover gaming books.
As I might have predicted, it has a green cloth bookmark, to contrast nicely with the red cloth bookmark with the PHB and the blue cloth bookmark with the DMG. It is a nice touch to use different colors, and a much-needed one because when the books are piled together, the black leather covers look similar, so the bookmarks set them apart. They also make a nice colorful contrast to each other in an almost artistic way that I find aesthetically satisfying.
Wizards must have heard some complaints about the pages sticking together at the ends from the gilded edges, because they do not stick at all with the Monster Manual - with the exception of a few pages very slightly at toward the binding, but those quickly separate, much like the PHB and DMG did. I must say I was slightly disappointed that I was not the one who separated them like I did with the prior two books (letting me know I was the first person to open it), but that is rather silly, since either way, once you use the book, they will be, and the books all come shrinkwrapped in plastic, so no one would be thumbing through it before me in any case.
All in all, this is a well constructed book that I expect to see heavy usage around my gaming table. I hope Wizards makes other leatherbound versions of heavily referenced books, like the Spell Compendium, because they are a joy to have and use.
(Minor confession - I bought two copies of each volume - one to use, one to put on my shelf next to my leatherbound Shakespeare and More than Complete Hitchikker's Guide to the Galaxy, just so I knew I'd have a pristine copy and so I could take my 'for play' copies with me without worrying as much about them, but they play copies are so durable I probably needn't have done so - and the pure visceral pleasure of opening and using these books at each game makes me enjoy those copies more than the pristine ones on my shelf).