It's always easier to feel something from a film when you know exactly how it feels to be in the situation yourself. For that reason, young adults who have been following the Toy Story trilogy since the first film will have done well not to feel a great deal during this film.
What makes the complete trilogy an emotional success is that the owner of the toys, Andy, is essentially a representation of the viewer. In Toy Story, his toys are everything, displayed in his exhiliarition upon receiving a Buzz Lightyear for his birthday, and the world he creates with his toys. I was a kid at the time and I loved toys too. Of course, the attraction to the film is the idea of toys coming to life which is a simple concept but had never been done so superbly until 1995. However, by the third film, it isn't the toys being alive that proves to be the bigger picture.
Following on the idea of Andy and the viewer being almost one in the same, Toy Story 3 is where it all hits home. It isn't idealistic and it isn't a cliche. Andy is now an adult and he's going away to college. Unfortunately, we're not kids forever and he has no use for his toys. What will have you close to tears—if not in full flow—is how closely we relate to growing up when we saw Andy going through the same thing. I challenge anybody who watched the first two films not to be fighting back the tears when the third film draws to a close. It isn't melodramatic and it isn't over-the-top. In fact it's incredibly simple and minimalistic. But watch that film and you'll find yourself feeling exactly what Andy does.
Pixar haven't just lumped on a sequel with this film like many franchises have done so recently. They waited the right length of time for this conclusion to the story, and I'm glad they did.