In short: it was awesome and I can recommend to stay at Marcello's wholeheartedly.
The apartment was very clean, comfy and spacious. It had everything we needed. The garden and the outside of the apartment is really beautiful and relaxing. And as for Marcello, he is a really amazing host. He helped us with everything, he had suggestions for everything and he was available the whole time either on the phone or in person.
It can be a bit tricky if you are planning to get around with public transportation (as we did). Expect (sometimes heavy) delays with buses, but the trains are very much on time. Also one of the neighbors have a rooster which can be a bit noisy early in the morning. :D We found earplugs in the drawer, but we didn't need them. We got used to it after the first morning and it didn't give us any trouble later on. If you are okay with these, you'll have a great time staying at Marcello's!
Thank you once again!