I've done a ridedrive course. My primary motivation was the 25% off discount with Adrian Flux. I coupled this with a pistonheads membership to get 35% off the premium so it basically paid for itself year 1 and the discount is ongoing. It actually turned out to be great fun and very informative. My instructor was a police advanced driver. He took me through some basic observation and awareness drills and then we did a full hour on track (with no one else there!) to get the balance and feel for the car. The rest of the road work through the day was useful - particularly the motorway and observational points e.g. line of sight to help you read an unfamiliar road. If you haven't done anything since your test (like me) and are driving a powerful car I wouldn't hesistate to recommend it.
Basically some practical tips on improving your driving, watching out for idiots, having fun on track and getting money off your insurance. What's not to like?!