We just spent several days and really enjoyed it. Expect a nice relaxing time rather than something very exciting.
Great for walks along the beach or the main street stopping for a drink or ice cream in one of the many cafes.
The Ostsee-Therme is also well worh a visit with several swimming pools, whirlpools, saunas, steam rooms and sun terrace. But notice that the whole sauna/steam room floor, including the top terrace are textile-free.
It also has a nudist beach (FKK) on the north side which was quite nice and well protected.
You are also 20 minutes away by train from Luebeck, which makes a great day visit with its medieval old town.