Note: This place is now known as "Séjours & Affaires Nantes Ducs de Bretagne". It's still just across from the convention center, above the Carrefour grocery.

I stayed here for six days and liked it very much. I would definitely stay here again. There is no daily maid service, but on check-in everything was clean. The sofa bed was of good quality -- I found it pretty much as comfortable as a regular bed. Internet was free and by ethernet (wired) so be sure to bring a laptop and not just an ipad or something. (They provided the cable.) The shower stall was narrow but equipped with a handheld showerhead with excellent water pressure and an adjustable mount.

Having the laundry room available was really great! You have to buy "tokens" from the front desk and it's 3 euros each to wash and dry, but it's totally worth it.

The staff were extremely helpful -- while I was trying to finish up laundry before I left, they even offered to start my laundry in the dryer for me while I ran out to dinner, so that it would be done in time. They also were really good about answering all my questions by email (in English) beforehand.

The location is perfect for the convention center. The kitchenette is great for keeping fresh fruit and grocery items from the Carrefour, and there's a bakery with great croissants just across the street (open every day except Monday).

The one drawback to the rooms is that there's no AC or other ventilation, although an electric tabletop fan is provided. On warm nights it's tempting to open the windows, but then there's often some noise outside and a risk of mosquitos (no window screens).

Also note that the rooms have no carpet. They do provide disposable slippers. I actually prefer this because I think it's cleaner, but others may disagree.