Hi, I am Ravindra, i was there in Mumbai in the month of June 2011 for a official meeting.
I stayed there in Hyatt Regency, it was a wonderful time i have spent in this hotel.
staff was good, room Amenities were perfect, food was delicious, overall i can say the best place to stay at Mumbai.

Starting with the pros,
GREAT BREAKFAST! so many varieties, and great quality of food.very tasteful.... they really make you feel that breakfast is the most important meal of the day lol
Room is spacious(club room tbs), often modernized compared to other hotels nearby. And love the odour of the corridor through the room!
very good service.
Cons,
not a hotel for pleasure travel, you'd rather should choose one located south mumbai.

typically hyatt! larger than life feel, top class ambience, feel special. dining: Stax is a fantastic restaurant, fresh and good quality pastas with decent variety. Glasshouse has amazing kebabs and curries. the rooms r spacious great, neat and clean too. pool is good too. located opp international airport, hence its fantastic for foreign travellers. a little expensive though. only 2 drawbacks: construction work outside makes traffic a nuisance, and avoid during the wedding season, lots of commotion and noise. otherwise, overall, pretty good.

i love this hotel .. its good for me to stay in this hotel as its near by airport.. the rooms are pretty good.. ambience is excellent .. hightly lavish property.. wish to stay here again and again.. bit quite expensive but still value for money..