"My initial feelings are pretty positive," he added. "The car feels reasonably quick."
But with every other 2012 car featuring a radical 'step' in its front nose, some reports believe McLaren may have missed a trick by opting for a conservative solution.
"It is not a trick or a loophole that we did not spot," said McLaren's technical director Paddy Lowe.
"Some people have some interesting ideas around the use of that step, and we are looking with interest at all of that stuff," he told the Mirror.
Actually, the McLaren was not far off the pace of Sebastian Vettel's new Red Bull, but the pair were a long way from Romain Grosjean's impressive Lotus E20, and the 2011 Mercedes driven by Nico Rosberg.
Vettel, also getting his first taste of his 2012 machinery on Thursday, admitted there are "question marks" about all of F1's regular pacesetters.
Nevertheless, "We are where we want to be," the reigning world champion smiled. "It feels fine and as we expected."
Agreed team owner Dietrich Mateschitz on a rare paddock visit: "It looks quite good but anything else would have been a surprise as the car is a development."
Britain's Daily Mail said the F2012 is "ugly in more ways than one".
"I can only say that it is going to take a lot of analysis to put all the pieces of the jigsaw together," said Ferrari's British technical director Pat Fry.
"I am not happy with where we are at the moment."
Arguably even less happy on Thursday were Force India's Jules Bianchi and Nico Hulkenberg, after the French test driver crashed the new VJM05 before setting a laptime.
There were not enough parts to repair the car and so Hulkenberg's scheduled track debut was postponed.
"I'm very sorry," said Bianchi, "because my mistake has cost the team a lot of time and effort."