You asked whether having kids makes me view kid flicks differently, and whether having kids makes reviewing a family film easier. To answer the first part of your question - to be honest, I'd have to say that my perspective on movies in general is inexorably affected by being a parent, especially when a film concerns parent-child relationships in any way. I remember bawling my eyes out when I took my then 2 1/2-year-old daughter to see Tarzan while I was pregnant with my older son; the whole "You'll Be in My Heart" sequence just tore me up. It's interesting that you used your niece's reaction to Finding Nemo as an example, because the opening of that film was upsetting to me as well. It's kind of a Disney thing to do in the mother within the first minutes of the film, though; I suspect it must be in the Disney Bible somewhere that the change that kicks off the movie should involve the death of a parent. That's a much scarier to most kids than the mythical boogie-man.
This experience is true for me with "grownup" films as well, though. In one of my favorite movies of all time, Douglas Sirk's Imitation of Life, the relationship between Annie and Sarah Jane - the normal separation of the mother-daughter bond amplified by racism and Sarah Jane's mortification that her mother is black - is really hard for me to watch. Innocent Voices was excruciating - watching Chava (Carlos Padilla) through the eyes of a mother, imagining living in that place, with the constant fear that with each passing year your son is a step closer to him being taken away no matter which way you turn - how could the mother in me not be affected by that? That's part of what makes movies matter to me, though - when done well, they give us windows to other perspectives, other cultures and ideas, and they help us see that some things, like a mother's love, are universal no matter what boundaries you live within.
So does all this make reviewing a film like Ice Age 2 harder or easier? When I review a family film, I try to compare apples to apples. You can't compare Ice Age 2 to, say, Hitchcock or Truffaut - how could you? You have to evaluate a film like Ice Age 2 against other family films targeting at the kid demographic, and yes, I think that having kids around makes it a bit easier to do this. My house is like a constant science lab, with children acting and reacting to what they see. I can watch my kids and observe how they respond to, say, March of the Penguins (my kids are still talking about the poor mother penguin being eaten by the sea lion and the fate of her baby and have integrated that into their play, I think as a way of working through it).
We own Ice Age, and my kids still like to watch it, so I was interested to see how Ice Age 2 would hold their interest. The youngest lasted about 2/3 of the way through., which either means he found it pretty interesting, or he'd slipped into a coma from the sugar content of the rare treat of a soft drink. The four-year-old was a bit scared of the "scary fish",and by about halfway through the film was requesting multiple potty breaks. The older two watched the whole thing, and they seemed entertained, but not as much as they were by Madagascar or Shrek 2. The nine-year-old is really more into films like Harry Potter, Aquamarine, and High School Musical these days, so her interest in films like Ice Age is waning, but she still laughed out loud at pretty much every scene involving the squirrel and his nut. Bottom line, I don't think parenthood makes it harder or easier to actually review a family film - I just have perhaps a different perspective on them than someone who doesn't have kids. Is this good or bad? Depends on the film, I guess.
So here's my volley back to you, Rocchi: how do you, as someone who doesn't have kids, review a family film? Do you draw on your own childhood to try to project how the film might have appealed to you at the film's target age? Or do you just review the film solely on its merits, weighing it mentally against all the films you've seen?