We have dined there many times over the years, even after hearing all the bad reviews.
We have yet to experience a bad meal there. My DS reallly enjoys the band, and loves going up to sing and dance. He's usually very shy about those type of things, but he has no problem participating there!
I think a lot of the complaints are because of the seating arrangements. Again, we have never had a problem with this. Our children have excellent table manners which definitely helps when you're sharing a table with strangers. I have seen people around us dining with unruly kids, and I think that detracts from the dining experience for some people.
BTW, the seating is just as it is at the real Oktoberfest in Germany, except these tables don't seat as many people.