With my family, we stayed in Elena's place for a month while visiting EPFL. The place was very good. Almost everything needed for one month stay was available and we had a very good access to supermarkets, bakery, food stores and pharmacy. It was also very close to Rennes Gare, so commutation between the apartment and the EPFL campus was very easy (just few metro stations).
Elena herself was very kind and responsive. She responds almost immediately after sending her a message. The apartment was completely clean when we got to the place and equipped with what you need for the first week which I found it very kind and nice. The regulations, important addresses and phone numbers were all listed on a paper and hanged on the wall. This makes it easy to get used to the place. The neighbors were also very kind. As we were there with my 3 year old kid, we were quite noisy; however, the neighbors were very friendly and kind to us. My kid also liked the place a lot!
If it would be a second visit to Laussane, I would definitely consider Elena's place again.