It's magic. You probably have to queue for day tickets, which means getting there around eight (or a bit before) and waiting until 9.30 for the doors, which I did yesterday. I quite enjoy that though, on a sunny day. It's one of those all-in-it-together kind of jolly, well-mannered queues made up of people who don't usually have to queue for things.
The only problem with day tickets is if you're seeing a show whose spectacle is not best-suited to front row seats*: London Assurance looks great, but it's not huge choreography and dancing mountains: front row is more than fine.
* I saw Much Ado About Nothing from the front a couple of years ago. One amazing moment in that production saw Simon Russell Beale, on verge of discovery, leaping into a pond. The moment was more amazing if you didn't even know there was a pond in the set because your eyes were too low. There was a sudden gracefully pratfalling leap, a fraction of sideways weightlessness I can still recall in the cathedral of my mind's eye, a confusion and a splash.