I've seen both the London version (about 3 wks ago) and the North American version when it was playing in Toronto in October-December. Brilliant and great fun.
On the whole I think the score from the London version was better, but obviously some of those numbers had to be re-considered for a North American audience (where Kylie wasn't the hit-machine she is elsewhere).
With a couple exceptions, the cast I saw in Toronto (most of whom have gone to Broadway) are a lot stronger. I'd never seen Nick Adams perform live before--just knew of him because of his ridiculously perfect body. I have to say, he's a really great performer, and one of the best at maintaining a fairly believable Australian accent! lol