For about fifteen years, here is what it looked like, looming over the city like it was about to fall over. Even the North Koreans hated it, and air brushed the building out of photographs of the skyline. The only reason they are finishing it now is because this building became known to the outside world through the internet, and they want to get rid of the embarrassment.
The glass on the outside simply covers the cement structure that has been sitting outside, exposed to weather for fifteen years. I can't imaging that the building is actually safe to occupy. They will probably build some hotel rooms in a few floors just to say it is now finished, but it will be unlikely to be occupied very much at all.
Here is a great video of the culture that created this:
There have been reports of masonry, glass and wood from this monstrosity falling into the streets for years. I’ve also heard the upper floors of the building are seriously out of plumb so, at some point, the top of the “pyramid” may simply topple over, or fall into the lower floors.
However, the building does serve one useful purpose. For years, it was the “aim point” for focusing the high-resolution optical camera carried on USAF U-2s, flying recce missions south of the DMZ