Had a joyless visit to Legoland today. I very much hope not to go again.
I would say that unless you are prepared to pay for Q-bots, don't bother going. The first ride, The Dragon's Apprentice, was pretty representative. A small queue, about 50 people ahead of us. Space for 12 people on each ride, and each ride taking less than 2 minutes. Sign said the wait time was 15 minutes. However, as the ride comes in, no one is rushed off the ride. The operative chats to the Q-bot riders - very slowly chats to them. Slowly scans the Q-bot. Slowly opens their gate. They slowly prevaricate over where to sit. They slowly get in, change their mind, get out, change seats etc. Now just space for 6 to 8 riders from main queue but only 4 to 7 let on. Always spaces left. So each ride effectively took 5 minutes to process very few people. Our 15 minute queue ended up being 55 minutes.
Every queue seemed to be majorly delayed by the Q-bots. Much to everyone's entertainment, at the Atlantis submarine the Qbotters have to merge with main queue and queue for 5 whole minutes. One woman had an absolute meltdown over this.
The final straw was the queue for the ladies loo (as an aside, full of boys aged 5 to 9 years - surely if old enough to queue on own, they are old enough to go in the Gents). So me and Dd queueing for loo and a 10 yr old swans in, past the queue into opening cubicle. People complain and she waves her Qbot at the queue and slams the door behind her.
Never again.