Yep, the rear windows are stationary. It would be nice if they were pillarless and retractable (like the E Class coupe), but I guess it's a small sacrifice. I assume it's for structural support that helps with rigidity and accident protection. At least the support is hidden by glass rather than a visual, painted pillar. I was worried about that big pillar making it difficult to see out the side windows, but side visibility really isn't a problem in this car if you have the mirrors set correctly.
A fully opening sunroof would be nice too, but the huge glass roof with the electronic sliding shade is great - more important to me than a sliding roof.
Trust me, when you get your car and have to manually close your trunk and slam the doors because they don't close correctly, you'll be griping more about those than the window/sunroof issues.