Regardless the fact that the entrance fee is 35.80 GBP (July 2025) this site is full of tourists, so there's no way you can visit this in all peace. If you don't like long queues get there early and do the popular things first: The Crown Jewels and the Royal Armouries and then the adjacent sites.
This really can't be missed. There is a ticket sale booth outside the site itself on the west side of the site, but online booking is probably a good idea, especially in high season. They are time slotted, but I was allowed to get in 10 minutes before my half hour window, so they might not (always) keep you to it.
The Crown Jewels are impressive and amazing. The Royal Armouries are equally impressive. There is a lot of text to be read. You can easily spend over an hour there. The wall walk gives you great explanations about the past and present of the site and all its different parts.
The site is very versatile, diving into different topics like war, history, archaeology, coin minting, culture, and whatnot. The poppy artwork representing war victims is another one of these.