I thoroughly enjoyed my tramp down and back up the 'Pozzo'. The stairs are very easy even though there are 240 of them. It is in excellent condition and remarkable in design and build for the time.
If you are not that fit, you can take your time. I must add thought the exit gate would be a challenge for anybody who is 'large' but I assume the entrance people would warn you on entry of that were a potential issue and if so, track back up the same way you came down as there is no discerning difference in the alternate paths.
Also an importand note for anyone with small kids which we did, we were not warned that it is quite dangerous as the 'windows' bases are quiet low and and enticing for small kids to peer over into the Pozzo and risk a very long drop if they lean over too far. There are no guard rails.
Anyway very much worth a visit.