I admit that this is the first game that I have seen Cam Newton play and it may be unfair to make a complete judgment based on such little evidence, but here goes. All I have ever seen of Cam Newton are the NFL-channel and Sports Center highlights. From those you can come to the conclusion that you are seeing a superhuman player. You see an Adonis of a man, seemingly bigger and more athletic than the little people around him. You see great speed and some elusiveness, great escapability and power as a runner. Then there's his arm - a real cannon; I saw many highlights of him throwing the ball 60 or 70 yards down the field (or so it seemed) with barely any effort to an open Steve Smith running behind the defense. That was impressive. But the highlights are only his top plays - I guess that's why they call them highlights. You've got to see him play a whole game, and really a whole season to see if he's really a great QB.
Based on this one very small sample, in a single sentence I would sum it up this way: with that veer/option offense, they're running a college style offense and he looks like a college QB. When he's got space he can make his throws, but when the pocket collapses a bit - not when he gets sacked, but when he doesn't have nice clean space to throw from - he's very poor and that's what separates the men from the boys in the NFL. Perfect example was the first INT by Hosely. Newton wasn't about to get sacked, but there was some penetration in the middle right at his feet and the pocket was closing in around him. He could not stride forward comfortably and use his perfect mechanics. Instead, he threw it just with his arm, did not get a chance to stride naturally and did not rotate his hips or shoulders on the throw. That's why the ball was about 3 yards behind the WR. Terrible throw and a good pick by Hosely when the ball got tipped in the air.
On his second INT, in addition to being a bad throw, it was a terrible decision - it was late and over the middle, a dangerous place to go and Boley picked it off easily. In fact if he hadn't made the pick, it appeared that two other Giants DBs were right behind him in position to do the same.
On the third INT, he didn't read the S coming over. That happens in the league, but it wasn't a crowded area, there was nobody else there, and the S wasn't coming off one man and going elsewhere. So even though these kinds of picks happen, Newton should have been able to see the S sliding in.
I also didn't like his attitude and behavior during and after the game. He finally scored a TD midway through the 3rd, Giants had the game well in hand at that time and he still went through his Superman performance. Wrong - not when you're down 3 scores. (By contrast, last year Cruz scored a TD against Saints when the Giants were getting roasted and he just handed the ball to the ref, did not do his signature Salsa dance. Professional.) Furthermore, Cam sulked on the sideline like a little-leaguer when it was evident that his team was losing. To top it off, his refusal to give the other team credit in the post game press conference, saying it was the Panthers who gave the game away, not the Giants who took it, was also childish and unprofessional. You don't display leadership skills to your locker rom by acting like a child. This is not college, where every person is within a year or two in age. There are some grown ups in that room. They're professionals. I don't think they like that stuff and they're not going to follow an immature kid into battle.