For those in the know, the UCB theater is known for focusing on the "game" of the scene. They are also known for having a lot of "rules" of improv. A lot of people hate this. I don't blame them. Their classes are especially adherent to the "game" approach and all of the subsequent rules, like "top of your intelligence" and "if that's true, what else is true." For people who tend to be more "left brainy," this can be incredibly difficult and stifling. For those who are "right brainy," such as myself, it makes complete sense to me.
Personally, I don't think the UCB method is good for everyone. It's good for a certain subset of people. If you take their classes and hate it, then go to another school. It doesn't mean you are bad or anything, it's just simply different strokes for different folks.
Here's a recent podcast from one of the UCB four, Ian Roberts, who co-founded the theater. In this podcast he directly comments on the negative feedback that the UCB gets. It's super interesting to hear his response to all the things I've been hearing all these years. Take a listen!