I loved the 7X when it wasn't broken (early serial number). Very efficient and flew like a sports car. Of course the dispatch reliability and lousy Dassault product support pushed us into replacing our Falcons with Gulfstreams.
First trip in the G550 was literally around the world. No issues but excellent Gulfstream support was in place (i mean showed up at the airplane) for each stop just in case. After 3 years our 2 G550s and G450 have been nearly flawless. Unlike the 7X, in the G550, if you get a CAS message, there is usually a work-around so you don't have to power down and then power up (we called it "re-init" on the 7X). If you do have a problem, there is a hotline you can call from the cockpit that connects you to a terrific support team who will work you through any problem. (yes they answer 24hrs a day).
G550 performance is pretty impressive compared to the 7X but it is at a price. It burns a lot more gas so be prepared for that. It is also has a bigger footprint so fitting it on a ramp/hangar when away or a home base hangar should be considered.
From the passenger standpoint, when we started flying the Gulfstreams we heard some passengers comment on how "cheap" the interior looked compared to the Falcons but we don't hear that any more. They are happy getting to their destination with no delays.
If Dassault released the 7X with bugs and expected their customers to be their test bed. They lost a lot of customers because of it. That said, I am sure the current 7X is a better product than it was and I only hope Dassault treats their customers better.
So to sum up, we are now a Gulfstream customer and are happy with that
Kevin