It is an agressive design by McLaren and I think there are positive signs of progress during the test, especially when you think where they have come from.
I remember their Octopus exhaust of a few years back which they trialled and couldnt quite land, at least the skinny design doesnt seem to be overheating and that most of their issues are fairly simple operational ones, which as a brand new engine provider with what they say is brand new technology, is not a surprise. You get the impression they are turning up the wick slowly and are not rushing. And to be fair, knocking in a 1.27 when you were spluttering around on days one and two isnt as bad as first glance, is it?
I suppose Barcelona will reveal a bit more of the aero pecking order so Ferrari will get tested much harder. I suspect Mercedes and Williams to show glimpses there.
Will be interesting to see if Ferrari can maintain pace at that type of track and to find out of Williams have come up with an improved car through corners.