In one word: fantastic!
I enjoyed a lot my stay at Gernot's place.
Gernot is a super welcoming host, I really felt as home. He has a great knowledge about San Diego and United States in general so he gave me useful suggestions to organise my journey.
We had some interesting conversations about our life experiences and he was so kind to offer me a couple of drinks!
The location of the house is perfect: one block away from Mission beach and the bay.
Mission beach is an awesome place, you cannot ask for more: amazing beach, surfing, bars and restaurants, shops.
There is a bus station on the way to the beach.
Definitely I recommend staying at Gernot's place, I hope that I can visit him again in the future.
Great experience in SD, thank you Gernot!