I used this for 4 attractions, and was so easy to use! If you can, make sure you screenshoot the QR code that you get provided with via email, as you'll need this every time you line up for your pre-booked tickets. Be aware - you can't just turn up to the top of the rock unless you're there first thing at 8am - I arrived at 11:45 and the next available group was 12:50 which will vary on the day. Either turn up early or be prepared to not go up straight away!