I was very pleasantly surprised by how much I liked Biergarten. I ate there last year with a friend for the Candlelight Processional dining package, and I honestly chose it because it was in the least expensive tier and is close to the American Gardens Theatre. I'm a vegetarian and I don't care for heavy foods, so I was not expecting to find much to eat there. Boy, was I wrong. There was a great selection of salads (both hot and cold), breads and desserts that I could choose from, and nothing I tried was too heavy.
The theming is nice, and as Amyality said, the entertainment is really cute.
One thing that puts people off is the fact that you are seated at a common table with other guests - around 10 people per table. I was a little nervous about that, but it turned out fine. My friend and I were seated with a family of six on one side and a couple on the other. The family was very talkative and outgoing, and we had great conversation and laughs during the meal. The couple was quiet and their body language made it clear they just wanted to talk to each other, and that was just fine too. It wasn't awkward at all; we just didn't talk with them, and we were all fine with it.