I had never seen this movie before. I found it to be fine, but I don't understand why it's great enough to be in the Top 100. I wonder if growing up during the heyday of the clean, sanitized Western (the 40s and 50s) meant that any movie that even slightly tweaked the formula, like Shane or The Searchers, felt like a revelation. For me, having grown up entirely in a post-Wild Bunch world, pretty much every Western is dirty and morally compromised now. It's not unusual anymore for such stories to be presented that way, and to me Unforgiven seems like a more complete treatment of the same themes Shane addresses, leaving the older film looking a bit redundant on the list. I also agree with Paul's take that technically this film is not nearly as accomplished as John Ford's work was, so if we want an example of a more classical Western we should go with one of his.
Glad I saw the movie, but it's a no. Also, yes, that kid is annoying as hell.