Where else can you see London in all its glory at 450 feet in the air? The Eye is the highest observation wheel in the world and took seven years to build (a little late, if you remember). It was built to commemorate the new Millenium and represents the turning of time: celebrating London's past and looking forward to the future.
After taking the 30 minute flight I can truly say it offers a breathtaking view of the city. You ride in one of the 32 capsules. The capsules are big enough so you can walk around and get the view in different directions.
If you are going to take the flight, book ahead at www.londoneye.com. Arrive about half an hour early and bring lots of film.