The Tinker Bell movies are some of my most secret guilty pleasures for viewing, and they've thus far exceeded my expectations. The animation is gorgeous and lush, the orchestral soundtrack is beautiful and really lends itself to enforcing the atmosphere of the film. Despite having commercial tie-ins, it's refreshing to watch a beautiful CGI film that doesn't rely on pop culture references and potty humor to earn laughs.
The other fairies take a backseat in this movie compared to the first, and the focus shifts to Tinker Bell's friendship with the well-meaning Terrance. Their friendship, as well as the friendship between the two trolls later in the film, does a decent job in mirroring the kinds of social hiccups kids can encounter (misunderstandings, overcoming fights, making up).
Another refreshing aspect of the film, similar to the first Tinker Bell movie, is Tinker Bell's resourcefulness. She is a character children can relate to (as opposed to some other popular female heroines in today's media); she suffers from a testy temper, can be overly self-critical, but she engages in critical thinking and problem solving to overcome her challenges instead of sitting back and letting others resolve issues for her.
I can see some parents may have an issue with Tinker Bell hiding from others that she broke the scepter as well as going off by herself rather than telling others where she is. It might be good to sit and discuss why Tinker Bell decided to journey alone, and what other things she could have done instead.