This is a higher-end hotel with great rooms and views from the higher floors. The restaurants and food are superior overall to the other hotels I have stayed at in Amman... That's the good part.
You will also notice that the paint and finishes in the lobby look surprisingly new.
This is the result of a suicide bomber who blew himself up in the lobby, killing a number of people. The Grand Hyatt is one of 3 hotels were hit by suicide bombers in late 2005. That said, I stayed there several times after the attack and they did indeed beef up security and other physcial security measures to make the hotel more secure. Good restaurants/room service fare. Excellent rooms in a luxurious setting. Improved physical security after the 2005 attack.
Overall, it is probably overpriced for what it offers and I would prefer staying at the Amman Marriott.