As many have noted, Lorenzo is a very good host and he does a great job with responding quickly to communication and helping with transport to get to the apartment.
Trastevere is a great location for seeing Rome. It has a more residential feel than many of the nearby tourist site areas, and there are numerous restaurants, grocery stores, pharmacies and shops in very close proximity.
The area can be lively, so in retrospect since I am a light sleeper I might have wanted to be on the third floor instead of the second because there are fewer windows facing the street, but the nice things is that there is that option! Also, you may want to make sure you understand from Lorenzo how to get the water temperature right on the shower/sinks because you might not otherwise think about that important detail.
Notable places we ate nearby are Vizi Capitali for top notch seafood, Dar Poeta for pizza, and Hosteria dei Numeri Primi on our first night for a very nice start to our stay.