I've been living a half hour from GN for the past 15 years and I've learned a little about it.
Golf National was designed by Von Hagge, though Chesneau claims credit for it. It is modeled more on TPC Sawgrass than on any links, huge mounding between and among the holes makes for great spectator viewing. The Albatross course is the tournament venue, and there are 27 other holes but nothing at all interesting or even well-maintained. The practice area is big and wide.
Most importantly for economic and practical considerations, GN has the infrastructure and the experience to host a major event. It is easily accessed from major arteries around Paris, it has abundant open space for parking and marquis. There is a hotel of several hundred rooms on site, and ample meeting rooms, restaurants, and various interior spaces. They have hosted the French Open, which is one of the bigger European Tour events, for the past 20 years or more, so they have had time to rehearse, and they have all kinds of power and communication cables installed underground around the property. All these things are actually more important to a successful Ryder Cup than the integrity of the golf course architecture.
Golf National is adored by the tour pros, but the appeal escapes my limited ability. Forced carries over water on the first two holes disqualifies it from being great in my opinion, and water also comes into play on three of the last our holes, and another one or two mid-round.
Since they were awarded the RC, the French Golf Federation has spent millions to augment the infrastructure and improve the course. Most of the work on the golf course involved drainage, irrigation, bunker stabilization, a few new tees and cart paths. The original design has been essentially unchanged.