It's funny you mention that, Dave - I too wasn't that taken with Angola when I first listened to it. Then I heard it played out on a big system and I *understood*. The track is a magic spell! It never fails to get a crowd moving. I think it's the handclaps myself.
Which brings me to an interesting question for you all: What track have you listened to and not bothered picking up, only to subsequently hear it on a big system and then realise that you must have it IMMEDIATELY, to the point of even nicking it off the DJ?