We really enjoyed our stay at Gabriela's. With the given instructions the dock was easy to find. The boat itself has a very welcoming atmosphere and you feel right at home after entering.
The dock is just a few minutes of walking from the next Metro/Tram station and in a few minutes you can get anywhere you like from there.
I would most definitely recommend the stay here and do the trip again, but I would try to book one of the bigger boats, as I am nearly 190cm and it can get a little tight in the bed- and bathroom.