Not sure... what are your system specs?
I'm running an old intel i3 1.9GHz with an nVidia 1050 1GB card, and I'm running on fantastic mode without any problems.
I re-created a male and a female character a few hours ago just to see what the changes were, and ran around on both of them and completed the first Joyce Abbot mission on each of them.
I have noticed that the animations are a little smoother, there are a LOT more trees and buildings, hrmmmm... maybe some more water areas and I did see one that seemed too bright at a certain time of day... other than that though I didn't notice any real monstrosities I can think of.
Oh there is one combat bug I found that every once in a while the distance will get messed up when fighting if you use a power to target and attack. Your enemy will snap to you, yet you will both fight each other as if you were still at a distance
That's all I've got at the moment.