Saw that yesterday - it makes me wonder where this idea of him becoming Vision came from.
It's been a popular fan theory ever since the Avengers movie came out. Even before it was released (and news of Coulson's death had been leaked), people were claiming there was a post-credits scene in which he was resurrected as the Vision.
Also, while it's a great sculpture, it doesn't actually look like Gregg...
From memory, I thought they'd done a pretty good job. But having compared it against pictures of him, you're right, it's quite 'off' in places (especially around his jaw).
Still looks nice though.