It's had fabric glued over it at some point, so needs sanding due to the glue marks.. but physically looks to be in good condition. I haven't tried to open it or anything though. It'll need the motor etc checking, and rewiring.
In my 4 years at a Main Stealer I never saw one come from the factory with a sliding steel roof, just like with Webastos etc, the cars were PDI'd then sent out to specialists to have them fitted before delivery to the customer.
I had an electric one years ago which I sold without ever fitting it, the lure of the cash was just too much. Mind you, people would love to buy one now for what I sold it for back then.