I think the movie matches the quality of Jackson's LotR adaptions, the actors are terrific and as compared to LotR the material is not stretched but extended the movie feels more relaxed and contemplative despite the numerous action scenes.
Despite of some changes it is very faithful to Tolkien. Radagast is not merely a great character who helps to narrativize typical first person narrator material, here the dangers that lurk in the East in Mirkwood, but also embodies together with the other two wizards the idea put forward in Tolkien's writings about the Istari (I merely read the fragments from the Unfinished Tales) that they matched the qualities of the Valar that sent them (Gandalf - Manwë - wise ruling; Saruman - Aulë - control; Radagast - Yavanna - nature). This is not trivial but rather essential as the idea that evil goes hand in hand with exerting control is a key idea in Tolkien's work. *
Gandalf's motivation to join the quest which he mentions in Rivendell is also not taken from the novel (Unfinished Tales - The Quest of Erebor).
All this helped to get rid of the stupid children novel aspects of The Hobbit (especially the elves are horrible in it) and when some have been maintained like the storm-giants it did not feel childish at all. Furthermore it weaves The Hobbit into the Third Age in general, i.e. the fight for Erebor is just one of many skirmished before the War of the Ring, which makes sense in-universe wise (the commercial real-world reason, to connect these films to the LotR adaption, is obvious).
* - Tolkien has been an anarchic monarchist (My political opinions lean more and more to Anarchy (philosophically understood, meaning the abolition of control not whiskered men with bombs)—or to ‘unconstitutional’ Monarchy.) which sounds strange but means that free people live together and are merely bound by traditions while their king is not some tyrannical absolute ruler but rather an ordinary guy who finds himself on a throne by the accident of birth. Of course he can misuse his power like any man and there are plenty of examples in the work of Tolkien but if he is a good king he is basically becoming implicitly elected, i.e. he knows that he is just an ordinary guy and only made king (in terms of content, not form) because his people trust him so he works hard to retain their trust.
The scene in the movie where Balin tells about how he joined Thorin after the Battle of Azanulbizar or Aragorn bowing to the hobbits in The Return of the King neatly illustrate this.
The trick of all this is that there is no real dominating boss but rather some form of conservative anarchism; people are free and merely committed to follow their traditions and a king is just one among these free people bound by tradition. Back to the examples of Thorin or Aragorn, you can clearly see how deeply committed they are to the duties they inherited.
One doesn't have to agree with Tolkien on these issues (I certainly don't) but I think it is essential to keep them in mind in order understand his work and his view upon evil.