From what I've read the transformations will be more "intense" like in the movies and not so... smooth. Compare how Optimus transformed in TF1 to WfC and you'll get what I mean. You can sense the motion and weight of each shifting part.
i'm sure transformation will still be quick so you don't feel like a sitting duck as you are being shot at, though it would be cool if you can choose your transformation speed by double tapping on the transformation button. weight is very important to me. in wfc you can feel the impact when a robot jumps. in dark of the moon they were light as a feather watching the teaser again and drools
I dunno, Grimlock's transformation was mentioned as being particularly painful and gruelling in the GI article, he is probably different in that regard to the more normal characters.
