Most people will go to Lucky or write about Lucky for its famous biryani. While my personal belief is that it is the best by far in Mumbai, I will try and talk about some other aspects of this restaurant.
Lucky is a place for tasty food and nothing more. If you've gone there expecting a fancy restaurant with high class crowd, then you're in the wrong place. Not to say that Lucky does not have good crowd; rather it has people from all walks of life eating at the place. They've got a newly renovated AC section, which is many notches up from the previous one.
If one gets beyond the biryani, Lucky has awesome a la carte options in mughlai fare - both veg and non veg. A superb selection of kulfies and faloodas is good enough to complete the meal. The pricing is total value for money and one never walks out of Lucky without a satisfied look on the face.
Some of the other benefits of Lucky, which I have enjoyed over time are the late night hours - its open till after midnight; and the valet parking - whose valets will recognize and greet you even if you have gone back after many years.
I just cannot end without the 'biryani'. There is something called the Dum Biryani, which is what they specialize in. All other types of biryanies (which are most common) are rice cooked separately and served with gravy. The beauty of dum biryani, as compared to that, can only be tasted/felt and not explained. And if you've not been able to experience the same after eating it, that's just too bad for you!!