Currently in NG+ and recording all the bosses for YouTube. This game even offers native ultrawide support! My final rating will probably be 4/5, many boss fights are just too easy, even on NG+ (except DLC).
Yeah, this took a bit of time and patience. But now I have all the tail weapons.
Walk backwards in medium distance to trigger its flight attack where it swoops down at you. Dodge to the side, run near the tail and quickly roll underneath it, far enough to stand still on the other side for a moment. The last part is important, if done correctly, the dragon will always try to crush you with its tail. You should be near it, but not take damage. Now you can get a few easy hits on the tail.