If you're solely in Xi'an to see the Terracotta Warriors, then the Kempinski is not a bad place for your stay. However, do note that the hotel is very isolated and sorting out transport to the city of Xi'an will be an additional consideration if you would like to explore more that the First Emperor's mausoleum site museum.
As the hotel is built possibly to house massive tour groups and accommodate big-number conventions and business meetings, the hotel is huge and can seem rather impersonal for that reason. Also, due to its huge capacity and pricier rate, it is not always fully-occupied so the room I got had a strange musty smell that was not helped by a malfunctioning air-conditioner. After asking maintenance to sort it out a few times, they did offer to change our room for us. However, as there were not many days left to our visit, we declined and had to suffer a stuffy, slightly pongy room for a few nights.
The bathroom drains also had a bad whiff of back flow from lack of use.
Food options in the hotel were limited to 3 - a very poor Chinese restaurant, a coffee house (where breakfast is served) and a German Bierkeller which was the only establishment that remained open beyond 9pm.
As this was a business trip for us, we often worked late and were not able to travel out of the hotel for meals, leaving us with no option except the Bierkeller for food. While the microbrewery made very good beer, it became a bit bizarre dining on German sausages and sauerkraut in the middle of nowhere near the Chinese city of Xi'an for the better part of a week.