Not all, but some insurance companies do recognise it. Even the insurance question aside (although it is a big one for me, as a 21 year old with a 2 litre engined car) it's worth doing anyway, as it's taught me some useful skills. Had I failed the test, I would still have felt I'd got a lot from the course.
Commentary driving is not a compulsory part of the advanced test anymore (hasn't been for some time), but partial commentary (just saying something like "I think that car is going to pull out in front of me" when you think it) is regarded as a good thing.