Well I just finished the final boss, and I beat every other boss before it too. It was quite fun. Eventually the bosses became too difficult for me though, so I had to use those scadutree fragments. After that well you know, everything became too easy. The difficulty I would rate this DLC is above Bloodborne but below everything else. Base game was far more difficult.
Overall a bit disappointed in the weapons, my preferred weapon choice didn't get any good options for my build, so in the end I used the same builds the entire game.
As for armor, I did change a bit. Funny thing I just learned. There is a certain helmet in the game that reduces the amount of hp your flasks heal. The helmet I used the entire DLC.... Guess I should read the information more.
Highlights of my playthrough would be kind of spoilers, but know I really enjoyed it. Mostly how the world weaves together.
Should be another few years for From Software's next masterpiece.