I took an American friend to see the Stump, and we went up the tower. The notice states that you must be of a sound constitution, and they ask you before you go up if you have a heart problem. it's quite a long way up a steep spiral staircase; once you have started up there's no turning back
The view from the top is exhilarating, well worth the climb.
My problem came when going down, the steep spiral stairs seemed more intimidating and some of the steps were quite worn. I was really glad to get to the bottom.
Glad I went up though, but think carefully if you have vertigo or don't like confined spaces.
For a similar but not so high view and easier steps, try the Maud Foster Windmill
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC