In a word, superb. We have rented apartments in Paris through others, but now that we've experienced Guest Apartment Services, we'll use only them. We stayed in the Primavera apartment, overlooking the Seine in a very convenient location. We initially thought check-in would be inconvenient, it having to be at their office location, instead of meeting at the apartment, but we thought this mainly because we thought we'd have to provide our own transport to the apartment. Instead, the checkin was very smooth and they provided a car to drive us and the person who showed us the apartment features. The apartment itself was wonderful, with all the amenities. We went in the winter (though it was not that cold during our stay) and heat was good. Bed comfort was fantastic. Also useful is their concierge service, through which you can book shows/restaurants. And finally, contrary to most other Paris rentals, they provide a mid-week cleaning service, and not only that, but cleaning is not an extra charge on their rate, and their rates are competitive. We'll be back!