They're a far more versatile in their play, previous sides have been all about pass pass and if you played the right way (like Chelsea) you could more often than not stifle them and restrict their chances, now they have pace and can be more direct, they also have several genuine goal threats whereas before they relied too much on Messi.
Personally I think they're more dangerous and have more goals in them now, honestly think their forwards will have a field day against our defence and only Cech will keep the score down, Suarez, Neymar and Messi that's an unbelievable front 3, most teams would love to have just one of those three (we would) and they've managed to assemble 3.
The fact is other than our keeper none of the areas of our team are that great, up front we're not great, the midfield isn't all that and neither is the defence.