Mark T.
Yelp
By the time I ended up in Copenhagen, I had already seen many panoramas from many high points in many different cities around Europe. As such, I was debating whether or not to go to this one. It was over a third of the steps being on the outside that sold me, just as something that should be experienced.
The climb had a few things that I found pretty unique. First, there are several "scenes" depicting something. I have no idea if it is historical, religious, or purely artistic in nature. Second, there is a warning light that will tell you if the bells are ringing (usually it is just a sign). Finally, there is an area where you can see all the cogs that power the clock.
As for the climb from a physical standpoint... there were only two places with extremely narrow and steep staircases, but other than that, while you might have to let a person pass here and there, it is not as cramped as some other such climbs can be. And, and only because I once encountered such a climb without... there are railings!
The climb outside is interesting. At the point where you will enter the outdoor staircase, you are going to be at a sufficient altitude to see pretty much everything you're going to see. You see a nice variety of city, rural, maritime, and the planes going in for landing too.
This is perhaps the unique thing, you can keep going for those extra 150 steps, in a spiral getting ever narrower, not so much for the view, but just because. But, if you do plan to take every last step, be prepared to wait in line a little bit as others make their way up to, and down from the top.