Yep! I’ve been so excited! 
According to the Wikipedia page, Ron Pearlman is cast in an as-of-yet unknown role, as is Doug Jones. I know for sure that Ian McClellen, Andy Serkis, and Hugo Weaving are recast as Gandalf, Gollum, and Elrond. There’s also a ton on the production planning del Toro has:
Del Toro interprets The Hobbit as being set in a “world that is slightly more golden at the beginning, a very innocent environment” and the film would need to “[take] you from a time of more purity to a darker reality throughout the film, but [in a manner] in the spirit of the book”. He perceives the main themes as loss of innocence, which he likened to the experience of England after World War I, and greed, which he says Smaug and Thorin Oakenshield represent. Bilbo Baggins reaffirms his personal morality during the story’s third act as he encounters Smaug and the Dwarves’ greed. He added “The humble, sort of a sturdy moral fibre that Bilbo has very much represents the idea that Tolkien had about the little English man, the average English man”, and the relationship between Bilbo and Thorin would be the heart of the films. The Elves will also be less solemn.
Del Toro met concept artists John Howe and Alan Lee, Weta Workshop head Richard Taylor and make-up artist Gino Acevedo to keep continuity with the previous films, and he has also hired European comic book artists to complement Howe’s and Lee’s style on the trilogy, including Mike Mignola and Wayne Barlowe, who began work around April 2009. He has also considered looking at Tolkien’s drawings and using elements of those not used in the trilogy. As Tolkien did not originally intend for the magic ring Bilbo finds to be the all-powerful talisman of evil it is revealed to be in The Lord of the Rings, Del Toro will address its different nature in the story, but not so much as to draw away from the story’s spirit. Each Dwarf will need to look different from each other. Del Toro will redesign the Goblins and Wargs and the Mirkwood spiders will also look different from Shelob. Del Toro felt the Wargs had to be changed because “the classical incarnation of the demonic wolf in Nordic mythology is not a hyena-shaped creature”.
Guillermo del Toro noted that John Howe’s illustrations of Smaug “approximate” his vision of the character. Del Toro also wants the animals to speak so Smaug’s speech will not be incongruous, though he explained portraying the talking animals will be more about showing people can understand them. Smaug will not have a “snub Simian [mouth] in order to achieve a dubious lip-synch”, and Del Toro notes that such is the attention given to him that he will be the first design begun and the last to be approved. The director, whose Chinese zodiac sign is the Dragon, is fascinated by the mythological species and attempted to include one in Pan’s Labyrinth, but was unable to for budget reasons. His favourite cinematic dragons are Maleficent in Sleeping Beauty and Vermithrax Pejorative from Dragonslayer. He has also provided a foreword to Howe’s portfolio book Forging Dragons, where he discussed the dragon’s differing symbolism and roles in various cultures and legends.
Ian McKellen and Andy Serkis (who played Gandalf and Gollum, respectively), have met Del Toro, and ideally, he wants every actor (including Ian Holm, who played Bilbo in Rings) to reprise their roles, although he acknowledged some may be unable to because of health problems; he would also consider having Holm narrate the films. Del Toro, in an interview with BBC radio has confirmed that McKellen, Serkis and Hugo Weaving (who played Elrond) will reprise their roles. All 13 Dwarves and Beorn will appear, while Thorin’s father Thr
