Hermitage's site in english might take a minute to load up on your computer. All known renders of their twins including interior ones can be seen there. Also a brief description of their contents in the mixed-use section.
Construction is officially planned to start in october although some are skeptical over here for now because of a confusing rumor saying russian company Mirax Group whose Hermitage is the french subsidiary would be struggling with some serious financial issues. Still Hermitage keeps on promoting their twins as if everything was fine, having already invested €150 million (over $200 million) in them.
This project alone represents a €2+ billion investment and 3,000 created jobs; it is by far the biggest real estate project seriously planned in France since long long ages.