Let me preface by weakly claiming to know authentic Pakistani food. I spent a couple of summers in Pakistan and certainly got my fill of authentic food (mostly in a good way but some serious stomach related side effects too). Anyway I went to Kabana with a friend who had rave things to say about it. I got the chicken jalfrezi and chapati. It was pretty good, but not worth the reputation and I have to admit you can tell an inauthentic Pakistani restaurant by the lack of chapati. So at least that was a real positive.
However there were two glaring problems.
1.) Cleanliness - There was a large sack on onions on the bathroom floor. God knows how much stray urine ended up on those onions. I've definitely had some authentic Pakistani food in Pakistan that had a similar level of cleanliness. I once ate at restaurant where forks were re-used without being washed. Kabana is better than that at least.
2.) Service - I can handle inattentiveness and even slightly hostile personalities, but I really hate incessant pressure to buy more stuff that I don't want. It's like having a mosquito buzz in your ear while you are trying to eat. In my case I was given more chapati without me having asked for them. This made me think since I didn't ask for it, it wouldn't be charged. I was definitely charged for all of the chapati despite only ordering the 1st piece. I guess their thinking was that chapati is near costless to make, so they should really get me to eat a lot. There was also near overwhelming pressure to order drinks and sides which I wasn't interested in. The pressure to buy was pretty authentic I have to admit.
So to what do I attribute the success of the restaurant? The usual desire of Berkeley folks to be open minded and part of a select group that knows the truth. The restaurant may be unpretentious, but the folks singing its praises frequently are (they presumably possess a deep knowledge of authenticity and sophisticated palettes that render them capable of looking beyond the obvious shortcomings). Indus Village around the corner on San Pablo Avenue is quite a bit better in my book. Their lamb shank is very good.