I went three years in a row, and it was awesome every year. I missed last year because they didn't come to our city for some reason. The first year was wonderful. Just my husband and I went and the show was really long (almost 4 hours), and they were great. They did a dueling piano bit that was my favorite.
The next two years we took our whole family with us, and they absolutely loved the show. We were a tiny bit disappointed, though, because it was a bit shorter each year. The third year was noticeably shorter and it lacked a certain "Christmas" charm--maybe because we saw it a few days after Christmas. Later we found out that half the cast had the flu, which really explains a lot of that.
I would take any age kid to this show, except for babies/toddlers. It's really too loud for them. Some people get a little too worked up/too drunk and start acting like they're at a rock concert, but most of the crowd is made up of families. They probably set up differently depending on the venue, but I wouldn't recommend any floor seats (usually the VIP section, I think). That seems to be where the most of the rowdy crowd sit. The obnoxious people are really few and far between. A lot of people will drink beer the whole time, but a lot of people won't. The ones that do normally don't show any sign of being drunk. One time I heard a guy yell "f***" from the floor section, and the performer actually told him to hush because it was a family friendly show. And another time we heard a bit of commotion behind us and realized that an older gentleman and younger man had gotten into some sort of argument, and they escorted the young guy out. That was all there was to that.
The show itself is so loud and entertaining that I seriously doubt children would have noticed any of these things. I was just paying extra close attention because my little brothers were there.