In this case, for me, it's the latter. That's not to say that the film isn't interesting, detailed or multi-layered, but the reason that was repeating in my head to see it again was 'it's really, really good.' But is it? Yes, yes of course it is... Speaking with a bunch of friends with whom I saw it the first time, a risky phrase was unanimously agreed upon, which was that we 'trust the Pixar team to do the right thing.' Needless (totally needless) to say that expectations were high, and frankly, they were surpassed.
Even though the film is what we come to expect from Pixar (the universal moral themes, the perfect balance between comedy and sadness, and visually stunning animation and action sequences), I didn't feel that I had seen it all before, and neither was it repetitive nor 'ordinary'. The film hits all the high notes, with perfect intonation, and with discipline and passion. As touched on before, the balance between humour and sadness is strong and impressive; the amount of emotions that the film displays and takes us through is varied and immersive, yet not overwhelming. The film executes such clever ideas with simplicity and ease, leaving us to feel for the characters rather than worry about the 'science' of it all, or even being worried about 'not getting it'.
The animation is constantly eye-drawing and detailed; the characters' glistening skin is particularly wondrous. And what great characters they are. Riley is brilliantly sympathetic throughout, even with her difficult mood swings, and the supporting characters are perfectly entertaining. One might think that the superficial nature of the characters (Anger is angry, Fear is always scared etc.) would become old quickly, however the fun never diminishes, thanks to a witty script, expressive animation, and very strong voice performances from the entire cast.
However, to top all this off, the real gem comes from the character of Joy, surely a strong contender in the list of Pixar's greatest characters. Even though we are inside the head of Riley for the majority of the film, and the events that drive the movie are essentially her reactions to her new world (moving from Minnesota to San Francisco), the story is Joy's. Being probably the most flawed character in the film (paradoxically, maybe), it's her journey we care about the most, and she ends up being the most in-depth character in the film, occasionally questioning her actions in the first half (well, the cynics will be), and becoming the most sympathetic by the end. Amy Poehler's outstanding performance makes Joy simultaneously the strongest and weakest character in the film (emotionally, that is).
After all of this, the freshness of the ideas, the simplified neuroscience, the technical brilliance (saying that, Giacchino's score is probably the most subtle thing in the film, exquisitely putting the finishing touches on the most emotional scenes), fleshed out characters and universal themes, all of this comes together simply to entertain us, to let us escape, and to release us emotionally, which it does by making us laugh and cry in an even and fair manner.
And you will laugh. And you will cry. And it is fun to do so. Thank god we're living in a time when Pixar is making these films.