Well, Vivid was suppose to be different. I don't really see anything wrong with it to tell the truth, but then again I'm not really that hardcore of a fan to notice or care for changes.
I was really hoping there would be a version where we see Nanoha in her 50s or something though.
I don't mind the difference in the art style. It's still cute, after all, and the VAs are the same. Let's just hope the fight animations deliver. Lots of fighting in the story, after all. I consider myself something of a fan of the Nanoha world.
Regardless of style, the animation quality is, ah, not good. At all.
Nanoha has always known for it's...less than spectacular qualities, you know. Just search around and look through Strikers and the others from the TV, you'll find mind boggling QUALITY by the bunches.