We stayed at this pension (by the way the name is written Gründner) after Villa Campana unexpectedly canceled our reservation. We really liked the Gründner with its big garden and big rooms, the owners helped us with everything: renting a bike, changing money. They also let us check out late afternoon for a nominal fee.
The rooms are big and very clean, with nice bathrooms. Breakfast is the usual, but we also got sour cherry strudel, which was delicious. Also a complimentary plate of fresh cherries in our room!
Probably the only thing against it is its location (900m from shore) as it's a bit far for walking. But if you care to drive a bit, or cycle, it's great, in a quiet residential area. Yes, the neighbourhood dogs do bark, that is their job.