Just finished the DLC yesterday. I thought it was slightly better than the main game (less copy-pasting of boss types and dungeon types, so it felt leaner and more focussed). Some really cool, more memorable bosses too - I loved the visual designs of Midra and Scadutree Avatar (the sunflower boss).
As for the difficulty, I actually felt over-leveled for most of the DLC; I was already level 200+ beforehand and by aiming to kill every boss in the DLC I did a lot of exploring and found a lot of Scadutree fragments. I'm guessing a lot of the difficulty complaints are pre-patch and also stem from not being high enough Scadutree level.
That said the final boss was really bloody tough - definitely one of the toughest in any From game for me. It was like hitting a brick wall of endless sword combos followed by holy light beam spam the first 10 or so attempts, so that prompted me to go back and get max Scadutree level using a guide map, and re-spec & tweak my build. Even after that the second phase still felt almost hopeless for the next hour or so, but eventually I finally managed to kill him with no heals left - such an immense feeling of relief and accomplishment that I just don't get outside of Soulslikes.
