He is very laid back in his approach, but he must have real flair for it I think, as has done really well with technical challenges doing recipes he has never tried before, whereas Holly, seems so neurotic with her obsessive weighing of things!!
It is quite funny the way they edit it so they have obviously decided Rob is Mr F*ckup and make a big deal of his errors, while Jason putting salt instead of sugar into his tiny buns was pretty much glossed over.
Yes Paul is super serious, especially when Rob's pastries were a disaster and Salty was all like "How dare he present those to me!!!" However I think it works with him and Mary being quite stern while Mel and Sue generally piss about having fun and are lovely to all the contestants.