We've had three stays at the Park Hyatt. One stay in a standard room another in a suite in the new building and a third stay in another suite in the Palace side.
Great if you like that class of hotel and are willing to pay for it. We stayed using points otherwise I wouldn't bother as I feel you can get much better value elsewhere. Plus I can do without the extra attention especially when you have to pay for it.
However, if you have top status can get upgraded to a suite and enjoy the fantastic free breakfast then it's definitely worth it.