Sorry guys, my Chinese typing sucks, so you can only deal with my bad English.
1st of all I think it's worth to spend the extra money to see the Imax 3d version. Many of the camera moves and angles are designed for the 3d version, so I don't think all of them would make sense in a 2d format (normal threater). You would be dazzed by the 3d effects for the first 10 mins, but when you get used to it, it helps you focus on the story since you won't keep looking at the detail. There's a need to do it full CG, so the monsters and the humans are existing in the same space (unlike LOTR). The story is very simple, so the length is about right to tell the story. The action scenes are exciting esp. the ending scene, they also help to ease the downsides of the CG.
For the CG itself, there're goods and bads. The facial and overall character performance is far better than Polar Express, but that doesn't mean the "uncanny valley" has been crossed. While the modeling, shading, lighting and misc. effects (hair/far are excellent!) look great, you could still see the dull look on characters from time to time. All the "money" shots are great and Beowulf looks great most of the time but as he is in so many shots, he sometimes look dull and his eyeline goes off. The most dispointing character is the Queen, she looks off right from the start. From her look, shading to the facial, esp. the facial expression, I hate to say it but there's no soul in there at all... And the charcter John Malkovich plays... what a weste of a good actor. He looks off and no use for the storyline. As for all the beloved Angeline, she looks great.. but only in the shots that the trailer shown. She looks like a different person or very "CG" in many shots... Like I said before, the shading/lighing is amazing, the modeling is there and the effects are great except thr blobby looking blood. I guess SPI might want to hire the ILM water effects team.
Overall, a huge leap from Polar Express or FF, don't watch the normal threater version, watch the 3d version!