We had a great time. The main pros were:
The breakfast is well worth the 15 CHF.
We arrived after checkin times and the process was super easy.
The room was large and clean and had a fantastic view of the lake. Sunrises and sunsets were beautiful.
The dinner and music entertainers were also great, good atmosphere.
For the cons (there aren’t many):
It’s a bit difficult to get to if you plan to be out past 17:00, but we managed a taxi from the bus station (20CHF). The Sonnenberg bahn stops at 17:30, and the city bus also. The only way up past dinner is to walk or taxi.
Other than that the only other complaint is due to the mixup for our room. But this is more a hotels.com issue. Their description shows a balcony but there is no balcony with the room option they have. We arrived thinking we had a balcony but we did not (even though our hotels.com reservation showed one). They do have balcony rooms, just not the one that was available on hotels.com apparently.
Nevertheless, we had an amazing stay and would definitely stay here again. Highly recommend.