Albeit a little "swanky", the hotel was a great place to stay in Frankfurt. The fitness center has a complimentary spa with aqua massage bed, hot stone bed, hot tub, sauna and steam room. Bring your bathing suit! It is not central to downtown Frankfurt, but only a ten minute walk.
For people who like 'bright' hotels rooms, you should know that the hotel decor was dark - black and purple everything.