I rated 4 because the sky was a little cloudy. Didn't get a chance to try the "tilt" as we were not told that we could use our ticket to do the "tilt". We thought we have to pay extra to do it.
We arrived late afternoon - no queues and plenty of room in the Observatory. The more or less obligatory photographs on admission and when doing 'The Tilt' are unnecessary.
The views were spectacular and the information boards were very useful. Would include 'The Tilt' as part of the normal admission price and allow people to take their own photographs.
Awesome views over the Chicago skyline and surroundings.