People should be excited, as a bonus to already great things happening we get something that is better than currently sitting where Neutron is.
Between the new 3D projection system and how dark they can make it in there and main theater changes, it could be very convincing. Betting a lot of it is us being shrink rayed and flying arouind Gru's lab.
--- Update ---
The post show area is pretty darn open. It only needs to accommodate the groups that just exited the attraction before they go into the giftshop area. Think music, lights and disco with minions on screens showcasing you with cameras and lots of Despicale Me themed details like a "Gru Ray" player and DJ table as seen in the end of the movie.