The word you're looking for is "reimagining"

Rating: 7/10 (11 December 2013)

I won't "review" the content of the movie in any detail, but provide some thoughts about how this film should be approached. I consider myself a Tolkienist (in fact I saw this movie on opening night because I secured a promotion deal with the local cinema: I spent four hours until midnight writing people's names in Elvish writing!) It is to be expected that many fans of of the original book will perceive this movie as a bloated, garbled monster version of the written story they loved. It is important to realize, before going in, that this is not simply "the movie of the book". This is Jackson's The Hobbit, not Tolkien's, and they are best appreciated as independent works. They represent different media, come from different centuries, and have partly different target audiences. The children's book was written before Tolkien had any idea of the grand trilogy to follow; Jackson had already produced his Lord of the Rings trilogy and somewhat understandably tries to make the prequels resemble it, in tone and scope.
One could argue that Jackson's Hobbit trilogy, when complete, will set up the LotR film trilogy far better than Tolkien's simple children's book sets up the literary LotR. (The change in tone from children's book to grand epic is VERY pronounced, even grating for those who try to read The Hobbit after finishing LotR.) Incidentally, Jackson's prequel trilogy apparently will not spoil the LotR trilogy the way the Star Wars prequels give away important plot points of the original movies. When finished, Jackson's six Middle-earth movies can be profitably watched in sequence of internal chronology.
To be sure, Jackson's Hobbit trilogy is "based on" the 1930s children's book in the sense that the characters have the same names and visit much the same places in somewhat the same order (though new characters and places are also added). Their basic motivations are also the same. But beyond that, one should not expect much "fidelity". There is hardly anything that isn't greatly embellished and vastly elaborated, mostly so as to allow for a FAR darker tone and MUCH more fantasy action (i.e., fights). The spiders of Mirkwood here approach actual horror, as compared to their rather more children-friendly literary counterparts (where we have Bilbo insulting them with silly "Attercop" rhymes).
The wizards' conflict with the Necromancer of Dol Guldur, which in the book happens entirely "offscreen" and is just briefly alluded to when Gandalf has returned near the end, is here actually shown. This is understandable; Gandalf would otherwise be completely absent for much of this movie. Also, Jackson's audience will already know that this is the start of the war with Sauron, and the all-important Dark Lord could not well be ignored. Tolkien in his letters noted how Sauron casts just "a fleeting shadow" over the pages of The Hobbit; in Jackson's movie the shadow is darker and deeper.
Entire new subplots are freely created and added to the story. The Elf Tauriel and her unlikely infatuation with one of the Dwarfs is clearly meant to add a love story where the book has none, and have at least ONE strong female character (no concern of Tolkien's when he wrote a story for children in the 1930s).
The continued survival of ALL the protagonists despite their endless brushes with death doesn't just strain credibility -- it utterly and completely banishes and eliminates credibility. We are left with FANTASY action in the truest sense, to be enjoyed for choreography, not plausibility. If cats have nine lives, a Jacksonian Dwarf clearly enjoys a three-digit number of lives.
So, viewed as an independent work, is this a good movie? Technically it is nothing short of brilliant, full of detail that can only be appreciated on the big screen. Smaug is, hands down, the best-designed movie dragon the world has yet seen. If I were a teenager instead of a ripe old 42, this wealth of fantasy action would probably have exited me no end. It is nice to see Legolas again, even if he is not in the book. I liked the sequences with the amorphous Sauron. Poor Evangeline Lily would however look better without those silly ears, which are simply too big and look just as fake as they are. Also, I'm not sure the hinted-at Elf-Dwarf romance adds much to the story. All things considered, I'll award Jackson's re-imagined "The Hobbit" seven stars.
There were also seven stars in Durin's crown, for those of you who can understand the literary allusion ...