Great location: The hotel is just right next to Siam Paragon (at the centre of Bangkok) and it's a good walking distance (& exercise) to Siam Centre (or the Central). Don't even need to bring an umbrella if it's raining! And you can spend a whole day (eating, shopping & spa) without the need to get into the horrific BKK traffic.
Room: I've stayed in the hotel twice, pool-access duplex room (got upgraded the 1st time, and just got the same during 2nd visit). Big room, bathroom, free internet access (limited devices)...
Food: Sunday brunch (both visits) - good food, can't even try everything... too full
Also tried the Sra Bua by Klin Klin, (both visits), wonderful experience again!
I travel quite often to bkk for vacation, and will definitely continue to stay in Kempinski and recommend friends to stay there.