This has to be close to the top in terms of an overall pleasant and mind-blowing experience as I've had in any place in Mumbai. Poush is adorned with traditional Shikaras for seating (traditional looking cane and teak tables and chairs available too), nice lighting, and traditional Kashmiri music playing on the system. Before even getting a menu, one of the Poush staff comes to your table and pours warm water out of a silver flask into a bowl while you wash your hands - your first clue that you will soon experience all around amazing service.
The dishes truly taste different than your normal North India fare - and although some of the dishes have common names (Rajmah), they have a very unique and distinct taste. Don't miss the Razmah and the Nadier Palak (Spinach w/Lotus Roots). For dessert, opt for the Shufta, a sweet concotion of dried fruits and nuts marinated in a warm saffron syrup. Not a meat eater, but their meat dishes do sound delicious for the carnivores out there.
This place would rock for an evening with your best buddies (they have hookah too) or as a date place as well.