Surprised ! After all the negative stories about transport and queues at security, emergency staff and all, I went to weightlifting and found everything perfect, no queues, the Javelin train from St Pancras International to Stratford International took six minutes, there was no trouble getting over to the Excel, the venue was well equipped with food stalls, the staff couldn't be more helpful and friendly.
Yesterday, allegedly a really busy day, I was at the hockey in the main Olympic venue. Just as good as before, the train was busier but the delays because of queue control were only slight. And security? Noticed that there were dozens and dozens of spare checkpoints, manned ready but not in use, just in case of far greater demand. Can't see there'll be any delay there, however busy it gets. The only slight problem at the stadium itself was one familiar to soccer fans; the half-time interval was not long enough to grab food from the nearby stands and get back in time. But it's only ten minutes in hockey, and the slowest wouldn't have missed more than a minute or two.