Most importantly to note, the balcony railing was missing one of the rails when we visited. I didn't think to check this very closely, and I was out on the balcony working with my little one when she came dangerously close to falling off, so I grabbed her in time. It is only 1 story up, but definitely something to check if you are letting your little ones play out there during your visit!
Besides that issue, this place works well. There's a lot of sleeping surfaces (three beds, a fold out couch, futon, plus a pack-n-play if needed) so a large group can really spread out. Access to the center of Lausanne and the train station are very convenient! Both a balcony and small "front yard" so you can enjoy the weather.
You can only wash laundry on Mondays, which isn't unusual to schedule laundry days for apartments in Lausanne, but can still be inconvenient. The fridge and (very small) freezer were pretty full when we arrived, so we didn't have a lot of room for our stuff. But overall, if I was coming to Lausanne again we'd definitely see if this place was available, and would recommend it to friends.