I stayed at the Lindner for 3 nights with friends and thoroughly enjoyed the experience. The hotel room was HUGE.. a large living area, large bathroom with bath and over bath shower and a separate bathroom. Very clean, very spacious, friendly staff, very quiet hotel. Location is overlooking the Main River and within a few minutes walking distance of the Sachsenhausen (Affel Wein area).
Negatives? Well my shower was a slightly tricky to get the right temperature but a quick call to reception sorted that. It was VERY warm in the hotel room though...and the aircon was obviously centrally set to a mid level temperature which wasn't ideal in the night time.
I stayed on the 7th floor and with only 9 rooms per floor its extremely quiet... never queued once for an elevator. Breakfast was expensive but plenty of places to eat relatively locally and much cheaper.
The walk along the river into the main part of the city is beautiful.