Many pros, and one con.
Kate's apartment is really beautiful, clean and modern. With two bedrooms and a large living room/dining area, it's great for families. The terrace with a view of lake was also a major plus. The apartment is well-stocked with all the amenities you could want, including a high chair and pack-and-play for young children (and speaking of young children, there's an elevator to get up to the third floor apartment, which is a bonus for those lugging strollers!). The location is also perfect - just a few minutes stroll to the lake, restaurants, grocery stores and the train station.
The con: the apartment is right next to the train tracks. Literally, right next to them. In cooler weather, this doesn't seem like it would be much of an issue because the windows seem to block much of the noise. But we were there during the summer _ a particularly hot stretch of summer _ and you really needed the windows open to help keep the air circulating (like most European apartments, there is no AC, but Kate did provide several fans). This generally was fine for me and my husband, but our 15 month old kept getting woken up by the trains. Eventually we just closed the windows and made due with the heat.
It's definitely not a deal breaker - truly, the apartment is wonderful and the location can't be beat. But if you're a very light sleeper or have a child with you, it's worth giving some consideration to.