Out of all the chapels I have visited all over the world the Sistine is by far the most beautiful and by far the most intricate when it comes to detailing.
You could easily spend 4/5 hours in here exploring and examining all the small little details around.
We got there for around 7.30am and there was no queue but as soon as it hit 8.15am the queue was all around the court yard. If you have the legs I would definitely recommend climbing to the top rather than taking the lift. You really can get lost in here.