Have stayed here a couple of times over Christmas New Year prior to 2012. The rooms are well furnished and comfortable and if you manage to get one on an upper floor you get marvellous views over the city or the river. Room sizes and layout vary but most are good. prices are slightly high but this is a 4* hotel in Frunkfurt, lots of business use so they probably don't mind.
food in the restaurant is very nice and good quality but again a bit pricey.
Staff are not unpleasant but very business like and it is possible to go a week without getting a good morning from them. Location is a bit out of the way albeit a half hour walk to the city centre, best choice would be getting the tram which stops about 5 minutes away.. The river is on the doorstep so this is handy and the walkways here are well used by joggers and walkers. Shops and restaurants in Sachsenhausen are about 10-15 minutes walk away.
The spa services are often fully booked in advance and prices are a bit expensive. The pool and health suite are good to use but not much provision is made for chairs or loungers especially if busy. Staff are not very good at stopping children (and adults) mking a nuisance of themselves in the small pool.