Our stay at Helen's place was perfect. The location is incredible - you really can't get any more central! It's the perfect little spot to stay while in Paris - small and basic but exactly what you need since you'll be spending most of your time visiting the city, and only coming back to sleep anyway.
My favourite part was check in - Helene lives a few floors down and was very laid back about our arrival. If you've ever spent a thousand emails and phone calls trying to coordinate a key handoff at an extremely specific time with a host, then you'll also appreciate avoiding all of that since your host is just downstairs at home!