I was able to save a few £ on my purchase compared with prices on the door. But it was frustrating having to wait almost an hour in queues to actually exchange our vouchers for tickets. We were asked to wait in the same queue as those that were buying tickets at the attractions, and than we had to wait again in humongous queues to get into the attractions (London Eye & Sea Life). Because this took 5 hours in total, we missed Tower Bridge which was mean to be our last attraction for the day as they close at 17:00 and we got there at 17:10.. so I recommend you give yourself plenty of time, especially if you are planning to visit more than one attraction and there is some travelling to do.