From the highlights I saw, both players looked impressive both offensively and away from the puck. Ovechkin should have the inside edge for the Calder over Crosby since he is almost 2 years older and has much more experience playing against men. I think it will take Crosby a little longer to establish himself and adjust his game.
There are arguments about who is in the better situation. Ovechkin will be out there at all key times and while his team isn't the greatest, most top lines in the NHL are pretty good. Crosby has better talent around him, but not nearly as much as has been hyped in the media. He could benefit if he gets in key situations or if the opposing team's top checking unit focuses on Lemieux's line.
There is way too much pressure on both of these rookies since they were both hyped up beyond belief. People say Ovechkin is the best Russian prospect ever and that Crosby is the next coming of Lemieux/Gretzky. If either or both of these guys get anywhere near that level, it would be impressive, but everybody needs to cut them some slack for a few seasons at least. They are only 18 and 20 respectively.
As for the Calder race, only 2 players in the last 20 seasons won it in their draft year ... Lemieux & Samsonov. Both these guys have a shot, but don't label them busts if they don't win it. Generally that award goes to someone a little older. Since it is extremely difficult for a draft year player to win this award, it will be that much harder for Crosby to win it considering that there is an entire draft class a year older then him breaking in and a bunch of guys drafted in the preceding years that are only getting in now because of the lockout.
My personal assessment is that Ovechkin is going to be up there with Kovalchuk, maybe better, but he is primarily a finisher and a fantastic one at that. Crosby is more of a playmaker and makes his teammates better with his vision. I also think Crosby will be a more complete player in the long run and will end up ahead of Ovechkin in total points over the span of their careers.
I could be wrong of course. I was always more sold on Spezza's overall game then Kovalchuk's. I knew Ilya was a scoring force, but he seemed to not be a team guy. He proved himself quickly in the NHL on a team starving for talent while Spezza lingered in the minors on a stacked team with an impatient coach. Seeing how much Spezza has improved his skating, maybe my earlier belief in him will come true. I think his playmaking abilities are near the top of the NHL.