It's really amazing that this huge museum is free to enter (donations appreciated). (There are some additional "experiences" which you can pay for, such as sitting in a Spitfire, but I didn't experience any of those.) Spread over several large hangars, it starts with an overview of the first hundred years of the RAF, then has sections relating to the two world wars and more modern times. My favourite section was probably the First World War hangar, probably because it coincides best with the period of history I am interested in. That hangar includes a number of early aircraft as well as some display cases containing uniforms and various artefacts. In the other hangars there were fewer artefacts but a lot more planes! It was a little overwhelming to wander about among them all - and it probably sounds silly but I was surprised how big they were! Most of the planes can only be viewed from the outside but there is one inside the first hangar which you can walk through, and some later on which have a high viewing platform so you can see into the cockpit.
There were various interactive exhibits dotted around, such as designing a plane and taking it for a test flight, and although a couple of them weren't working, I thought they were good on the whole.
Although I love museums and history in general, aviation history isn't a central area of interest for me so I didn't spend overlong reading the display labels and detailed technical specifications of every aeroplane, but I still spent nearly 3 hours just walking around. If you are a real aeroplane buff you could probably spend double that amount of time. It would be churlish to give it fewer than 4 stars.