My call for an exception was to those making remarks that there is nothing at all to be concerned about in bringing a four year old to the movie (I did not express this clearly, I was a bit rushed). Of course being a parent is not automatically a guarantee of good judgement, nor is not having children a guarantee of the reverse (I've been a teacher for 20 years--at one time or another I've taught every grade from Jr. Kindergarten to undergrads and I only had children after moving to the older end of the teaching spectrum). My point was that I believe there is a very high correlation in this thread between lacking any concern and not having children.And, as a point of curiousity, how many in this thread who have expressed NO reservations whatsoever about a 4 year old at this movie have children? I'd wager none of you. And while I am usually a very staunch defender of the notion that you need not experience something first hand to have a useful comment, in this case I'd call for an exception.
I'm not sure if simply having children automatically means that you will be more sensible with them than people who aren't parents. Having worked in social services, special needs education and now in pediatrics, I have seen some catastrophically bad parents on the one hand, and some great doctors, nurses, social workers and teachers on the other hand, who were childless but absolutely great with kids. Some of them of course had loads of experience with children but some were young and inexperienced and still had a lot of sense about them and were able to deal well even with very troubled and troublesome youngsters.
To be clear, I think parents have the right to decide what their kids can watch and I intensely dislike having decisions like that made for me. However, the OP asked for an opinion and I believe, in this case, being a parent allows one, in the aggregate, to have a more informed opinion than not being a parent. Based on that, I made my recommendation (against going to the theatre, and for the DVD option, if the parent deemed the film suitable at all). I stand by those points. The appropriateness of the content is (and should be) the parent's decision. The venue where the content is viewed, however, needs to take more points into account and common sense strongly suggests a home viewing environment for this film for someone so young is FAR more preferable than the cinema.