This was the 1st AirBnB experience for my boyfriend and me and we had a really great experience! Stephane was very communicative and checked in at all the right times. He also left a nice note welcoming us to his apt and Lausanne, and which outlined the expectations clearly.
The loft itself was a very clean and spacious studio. The bathroom was large and everything we needed was easy to find (bedding, towels, toilet paper, paper towels, etc.)
There was no air conditioning (standard in Lausanne) and we stayed in August--it's on the top floor so it could get quite hot. However there are plenty of windows (offering great views of Lac Léman and fresh air) and we really only used his apartment as a place to shower and sleep. The bed was very comfortable and there was a window right beside it for a lovely nighttime breeze.
Pros: spacious, clean, comfortable, great views, ease of use, Nespresso maker, fast wifi, close to grocery and the lakefront, easy communication with host Stephane
Cons: No air-conditioning (it just so happens we visited during a very sunny week so we count ourselves lucky, overall)!