I'm watching Ted's Notebook and a couple of things stood out for me as he was showing pictures of all the cars:
1) The back of the Red Bull is tiny, they've clearly really pushed it to the limit.
2) The Ferrari, to me at least, looks like the most aggressive package. They seem to have found something with the cooling, with tiny sidepods and air box, and the shape of the whole car is very extreme. It was shown after the Mercedes and I was surprised to see the difference between the two.
Some of the pictures shown were from angles I haven't seen before and quite revealing, it's worth a watch.