Hotel is located on the 40+ floors of one of the tallest buildings next to office area and major intersections.
I got a feeling that no location is good in Beijing because everything is spread around non-walking distances. For example if you decide to live next to the Forbidden City then next day you don't really know what to do around there, neighborhood is hardly attractive. You may choose to stay in Grand Hyatt on main shopping street but is it really what you want to see in China. And prices for everything in Beijing are hardly attractive. So everywhere you go you need a taxi and access to main road. From this point of view Park Hyatt is more or less OK. You are about 20 min drive to anything from geographic center. And don't forget to call and set up a time for a taxi. If you simply go down from your 45th floor you'll find yourself in a priority line for hotel guests and spend there anything from 5 to 20 min.
Rooms are fantastic. Just look at pictures. And bathroom is out of this world (huge custom made bathtub and shower like Niagara falls water pressure) with the latest fully automatic toilet from Toto. Initially it took some time to realize that lid opens and closes as you approach this sanitation computer. I carry Hyatt Gold card and on Saturday morning I was offered upgrade which was a nice surprise. Thus on pictures is an upscale room but previous was OK too.
Good popular night club in the building where young Chinese drive their Ferraris to listen to live music from a nice band.
Problems. Only one major problem with China in general and even Hyatt. English. Even operator speaks with such accent that it is hard sometimes to guess and you should rather use plain loud language. Never leave hotel without hotel card with address in Chinese. The only solution for big issues is expat front desk manager, don't be shy to ask for him, great guy.
Overall great value for money. And try in the basement of the building Sunshine Kitchen, all delicacies like chicken paws and black fungus.