I just got back from the very busy show in London. Lots of "oohs" and laughs (some unintentional). I got in for free, but paid for my wife, who had a good time as well.
TOS-R looks fantastic on a big screen, the quality of the new effects and the cleaned-up footage holds up well. I even noticed something new about The Cage. Several of the crew members have injuries from the previous mission that dialogue implies became a fierce battle. One of the bridge crew has his hand bandaged, a Landing Party member has a dressing on his neck, and Spock himself is limping! I'm surprised I never noticed this before.
The cleaned-up footage on the big screen also had an unintended affect. The line of Shatner's hairpiece was clearly visible on one close-up!