The second installment of Peter Jackson’s flamboyantly puffed-up three-part adaptation of J.R.R. Tolkien’s little children’s fantasy book continues the feeling of disappointment engendered by its predecessor “An Unexpected Journey.” Providing a riot of action but little more than that, “The Desolation of Smaug” is big and visually opulent but oddly lumbering and dull. Even setting aside what fans of the author will consider tampering with Holy Writ—the addition of characters, some from Tolkien but others entirely new, and episodes (mostly derived from the author’s ephemera)—the picture fails on every level except as a serial whose twelve parts have been crammed into two-and-a-half hours, only to end inconclusively anyway. “The Hobbit” is beginning to bear the same relationship to “The Lord of the Rings” that the second “Star Wars” trilogy did to the first three movies–grossly inferior.

On a positive note, the picture looks better than “Journey” did. Perhaps that’s because the makers have foresworn the “revolutionary” 48-frames-per-second format that undercut the visuals of the earlier film and returned to the standard 24fps. But in any event the images are clearer and have greater heft, which—given the general excellence of the CGI work (with the exception of the technique for transforming ordinary-sized actors into dwarves, which might have entailed enormous effort but still doesn’t look convincing)—is a substantial improvement.

On the other hand, the carryover characters remain persistently sketchy and uninteresting. That extends even to the wizard Gandalf (Ian McKellen), who was genially engaging in “The Lord of the Rings” trilogy but here comes across as a grumpy, much too serious fellow, and the increasingly heroic hobbit Bilbo Baggins, who remains a bland figure despite the best efforts of Martin Freeman to invest him with some backbone. But it’s particularly true of the dwarves, few of whom emerge from the pack with any distinction. The major exception is their leader Thorin Oakenshield, who, in the person of the undistinguished Richard Armitage, is again a guy it’s very difficult to warm to or care about.

Perhaps realizing that this basic company needed some outside verve, Jackson has added to the journey an old friend from “The Lord of the Rings”—the elf warrior Legolas, again played by Orlando Bloom. It’s nice to make his reacquaintance, even if he doesn’t get much chance to do anything but wipe out arrays of evil orcs with his arrows or his blades. (It should be mentioned that those CGI orcs must be numbered among the most ineffectual villains in history. Though there are apparently hundreds, if not thousands of them in pursuit of our heroes, they manage to inflict but one injury—an arrow wound—while scores of them fall victim to swords, shafts or other implements of destruction.)

Among the other newbies are Bard (Luke Evans), a stalwart bargeman who helps the troop at one point, and the dissolute leader (Stephen Fry) of his his fallen-on-hard-times community of Laketown. Of the two, Fry is much the more amusing, but there’s very little of him. There’s a good deal more of Evans, but apart from having a handsome face on the screen it’s to little effect. Another new character—a thoroughgoing invention of Jackson’s—is Tauriel (Evangeline Lilly), a female elf warrior who’s the apple of Legolas’ eye but takes a fancy to Kili (Aidan Turner), the most ordinary-looking of the dwarves, choosing to tend to him after that arrow wound. Tauriel adds a female presence to what’s otherwise an ostentatiously male-dominated fantasy, but seems little more than a sop to the distaff side of the audience, an elf version of Katniss Everdeen.

As to the actual quest narrative, it takes up—after a prologue showing a pre-“Journey” meeting between Gandalf and Thorin, which explains to some extent the rationale behind the entire enterprise—with an encounter with a shape-shifter named Beorn (Mikael Persbrandt), who’s actually a fairly nice guy except when he’s a ravenous bear. After that Gandalf goes off on a separate search that eventually leaves him literally hanging in the presence of some unnamed but powerful personage while the others continue through a dark forest. There, after a creepy encounter with some giant spiders (an event that leads Bilbo to resort to using the ring of invisibility for the first time), they’re taken prisoner (as they often are) by the elves, but escape in barrels down a raging stream, depicted with such crowd-pleasing excitement that you could swear it was a test run for a “Hobbit” amusement-park ride. Then they have their Lakeside sojourn with Bard, followed by the denouement—a confrontation with the dragon Smaug, who robbed the dwarves of their kingdom inside a mountain and now slumbers amid his horde of coins, gold and jewels. Their purpose is to use Bilbo’s skill as a thief to secure an object called the Arkenstone, who apparently has some great mystic power. Exactly what will presumably be revealed in the third film.

All of which comes across as tiresomely repetitive, however expertly it’s rendered from the visual standpoint. The ultimate letdown comes in the big sequence with Smaug, a beast that looks wonderful and speaks in a boomy voice provided by no less than Benedict Cumberbatch, but turns out to be an arrogant gasbag who discourses endlessly about his power and intention to kill the intruders. He’s as boring in his way as those ineffectual orcs, who are always catching up to the band of heroes but never catching them (they’re the equivalent of the Indians in old Hollywood westerns who would attack the wagon train only to be systematically mowed down).

The movie finally comes to an end after 160 minutes, with Bilbo intoning “What have we done?” (a line the filmmakers might justifiably ask themselves) and none of the story threads brought to a conclusion. That’s par for the course in such second-of-three-parts series, of course, but in this case the appropriate response, given the colorlessness of the characters on display, is “Who cares?”

But one does have to salute anyone who has the guts to title a movie “The Desolation of Smaug,” which certainly won’t sound very inviting to anybody who hasn’t read the book. Unfortunately, the desolation this “Smaug” visits is mostly on the audience.