And so the juggernaut that is Peter Jackson's The Hobbit trilogy continues, Part 2 rolling into town like the eponymous dragon, pumped up by its power, breathing fire at anyone unfortunate enough to be standing before it.

One of those is the diminutive hero Bilbo Baggins; how we wish we could have a story befitting his size and lack of ego.

My objections relate to Jackson's approach to adapting Tolkien's precursor to The Lord Of The Rings. By combining fidelity to the single volume with equal amounts of additional material - designed to connect Bilbo's adventure with that of his cousin Frodo in the later trilogy - the obsessive director has turned what would comfortably have been one film into three, and a focused and predominantly light tale into something sprawling, dark and really quite wearing.

Although The Desolation Of Smaug is a massive improvement on its predecessor, ultimately it suffers from the same weaknesses. It picks up with Gandalf (Ian McKellen) and Bilbo (Martin Freeman) still accompanying the band of displaced dwarves led by Thorin (Richard Armitage) in their expedition to the Lonely Mountain, where the dwarves intend to regain their kingdom - and gold - from the dragon Smaug, in residence since he laid waste to the place years before.

Their passage is treacherous - orcs are on their trail, woodland elves and giant spiders bar their way. But they will find allies in two elves - Legolas (Orlando Bloom), whom we know from The Lord Of The Rings, and Tauriel (Lost's Evangeline Lilly), an additional character of Jackson's invention (created in large part to bring a female face in to the overwhelmingly male tale). As the dwarves reach the mountain and encounter the dragon, Gandalf makes a detour to confirm his suspicions that the dreaded Sauron has returned to the land.

There is, certainly, much to admire and enjoy. Some of the set pieces are brilliantly executed, particularly the encounter with the spiders, a river-borne escape from both elves and orcs, Gandalf's confrontation with Sauron (rare for its simplicity, a pure battle between light and darkness) and the introduction of the dragon, as a mini-mountain of gold falls away to reveal the giant creature's body.

New characters add emotional depth to proceedings, notably Bard (Luke Evans) from the human Laketown, clinging to survival in the shadow of the mountain, and Tauriel, a warrior woodland elf with a good heart and an amorous eye on a dwarf she deems to be a little taller than most. Freeman is again spot on as Bilbo, especially as the hobbit becomes seduced by the ring that came into his possession at the end of the last episode.

Visually, there is also an improvement. Whereas Jackson's specialised filming technique and 3D format appeared horribly bland before, there is greater depth to the image this time, making the film richer and more pleasing to the eye.

But from the running time (a whopping two hours and 40 minutes) to the messy climactic battle with the dragon and the constant cutting between storylines and protagonists, Jackson's propensity to over-egg never goes away. The single most glaringly bad decision is to put a vocal effect over Benedict Cumberbatch's voice as Smaug; the actor's innate ability to convey reptilian malice is neutered by the meddling.

Nevertheless, as Smaug flies menacingly towards the human town, one is reminded of the pathos and profundity Tolkien gave the latter part of his tale. Jackson has done just enough here to make me look forward to the next instalment.