The exhibition itself consists of a darkened room with one strong flood light and heavy rain falling from the ceiling. A computer system tracks your movement through the rain and creates a space around you so that you remain dry. The artist's statement explains that the viewer can experience what it feels like to control the rain. Rather I found that the rain was controlling me, as you need to maintain a snail like pace for the computer system to keep the space around you dry. Also the strong, directional lighting means that if you turned around to face the entrance the illusion is basically ruined, as all you see is a queue of people squinting awkwardly in to the light. However, in saying that, we both really enjoyed ourselves and agreed that we'd recommend it to anyone willing to queue in the line without begrudging it. If you visited Roger Hiorns Seizure, which involved queuing outside in the freezing cold for over an hour, you'll find this a walk in the park.
Also, if you haven't yet done it, check out the conservatory. Which I am told is the second largest in London (if that means anything). It's pretty run down and shabby looking, but still worth a look. It's somewhere between a grandma's garden and the Jurassic Park compound.
