We visited in off season and pre-booked tickets; no problems with the online booking process but a bit surprised at the €5/ticket additional fee for advance booking - almost like a penalty for planning in advance lol. That said, it is definitely well worth the cost as there was a constant influx of people around 1030am and when we left 3-4 hrs later, significantly more, literally seas of crowds due to the vast number of tour groups. We arrived a bit earlier than expected and were allowed to enter 1030am for our 11am timeslot, which was fantastic as there wasn't much else to do nearby that early. Once we got inside, there was no time limit enforced.
We also had a bit of a hiccup entering that was resolved very quickly - I brought my tickets on my phone as the original PDF they were emailed as. The tickets didn't scan at the automated gate, nor a staff's hand scanner, and so the staff member had to print my ticket off the computer in the booth. The staff were able to get this done quickly and were kind throughout. I saw other people with printed versions of their tickets get through the automated gates smoothly, so I recommend doing that just in case.
The museum itself is huge, has lots to see, and the building interior is very modern/clean and well suited for large crowds. Exhibits are mostly one way traffic - some wings we could see there was more to view, but could not access it unless we went back to the intended entrance. Signage for wing names is very clear which helped us ensure we didn't miss anything, but as other reviews mention, the Sistine Chapel is intended to be last. Lighting is decent and allows for good photos, but no photos are allowed in the Sistine Chapel.
I happened to have bad heel pain on the day I visited the Vatican, and can confirm there are many benches scattered about to rest at. That said, it is a huge museum - there is a lot of walking, many stairs, an overwhelming amount of things to see, and so it might be tough on older / disabled / injured people. Perhaps even too much for children as it's a long visit and took the better half of the day self-guided. For that reason, I was glad I didn't opt for a tour or audioguide, as that would have likely made the visit even longer.
As for the wings themselves, there's a good variety of items that you would expect to see in an art/history museum of this size. Some early excavational items, statues, limited objects from other cultures/regions, contemporary art, etc. I've visited a good amount of specialized / broad genre history and art museums and while not many pieces in the Vatican Museum blew me away, I did find some wings very enjoyable and think there's something for everyone.
Personal favourites for me were the Greek/Roman sculpture wing and specific works: the Laocoön and His Sons sculpture, the Pieta, the exhibit with black/terracotta colour vases like the ones in God of War, etc. Also I found myself quite mesmerized by the variety of painted ceilings, the mix of 2D/3D elements used , and the variety of lighting used for rooms with paintings, the lit ceiling hallway in the Gallery of Maps, etc.
When we arrived at the Sistine Chapel at the end of our visit, honestly we were a bit desensitized to all of the frescoes, painted ceilings, etc that we had seen all day. That, along with the intense, suffocating crowds in the Chapel made us leave in under 5mins. Even in retrospect, while I admire the Sistine Chapel a lot, in terms of the actual frescoes, I personally enjoyed other basilicas/churches more.
We passed by the gift shop, which was expensive asf but had lots of unique items like reproduction busts, etc. The items can be seen online but prices soar far higher compared to other museums, other basilicas, and even the Vatican's own St. Peter's Basilica. I was tasked with buying an official rosary for a religious family friend and luckily had bought it at the St. Peter's Basilica where the gift shop was uncrowded and prices were in line with all other basilica gift shops in Rome.
All in all, for the casual tourist / non-art enthusiast like myself, I'd say buy tickets in advance to skip the ticket booth lines, research in advance specific pieces you want to see + the exhibits they are in, download a map of the museum online, and book a time when it's less busy to fully enjoy the Vatican Museums. Even if you have to go super early/late, its worth having some peace and quiet to appreciate the works read more