Veronique C.
Yelp
The visit is included with the admission ticket to Windsor Castle and I would recommend booking in advance as lines can be very long and you may not get an entry depending on the time you show up at the entrance.
Also included is an audio commentary (in your choice of language), each explanation is around one minute long, perfect to understand what you are looking at.
Make sure you check the website for opening hours as some days the castle is open but the chapel is closed and they tend to end the visits early afternoon.
Inside, the chapel is a lot more impressive than I expected, much bigger and more like a mini cathedral.
Another way to discover it (although you don't see as much) is to attend one of the services sung by the chapel choir, and accompanied by the organ. When we went, the service was happening at 5:15 pm on a Sunday, we had to wait at the gate around 5 pm and it ended at about 6pm. Surprisingly, it was not crowded and it's free. It was an impressive experience, the voices of the singers so powerful and beautiful.
Whether you go to the service or not (I recommend you do!), St George's Chapel is worth a visit!