Taxi to and from the airport will take 15 minutes. As far as taxis are concerned, Darren and Peter41's ideas are good. Yet there is another possibility: The Grand Hyatt operates limousines to and from the airport, it will however cost a fortune compared to what the regular taxis cost. For the return you don't even need to go to Galleria Shopping Centre in order to make appointments with taxi drivers. You can even make them at the GH taxi parking.
As far as reviews of the property are concerned, it is IMHO simply one of the best resorts worldwide! The grounds are simply faboulous, service good (I personally don't need much service at a resort) when you're there for over a week they even know your name! I would reccommend to do the show dinner buffet in the evening. It is good and you can eat as much as you want! Breakfast buffet is subpar at this property. The Continental Breakfast at the Grand Club is better as in most other Grand Clubs and you can even order eggs as you like them. If you stay in a suite, Grand Club access is included.
@RTWStaralliance: Please have a look for me if the new Japanese restaurant is already open. If you want to eat Teppanyaki, the best cook at their restaurant is Mr Sarjono, greet him from the "Luxembourg-people"
Muerz