Our group visited here and found the whole experience very interesting. From getting our tickets at the bus station to the coordinated way in which 6 buses all managed to get up the mountain was impressive in itself.
Once off the bus you have to give a return time to get a ticket down. They reccommend two hours to look around.
You enter a tunnel and are then transported up in a lift. It was busy the day we went. It was a glorious day too and because of that the views from the area above the building itself were phenomenal.
If you are a history buff then there are some interesting pieces of information on the wall along the "Sun terrace". (Left side of building as you look from the rear) Other then that it's a restaurant and there us a nice area to walk up to above the building.
Bus back down
Enjoy the view