There is a strong reuse of enemies from the base game, which is disappointing. The new regular enemies are fun, but there aren't that many. Also what is up with From reusing so many things from Bloodborne so blatantly, even reusing names. It feels weird.
The bosses aren't really as hard as people are making it out to be, yet the criticism rings true. There is a point where the fights just get old and samey. You either do the dance and wait to get 1-2 hits in and the do it again, or use shield or parries and pretty much ignore everything.
Boss design in the DLC is competently done but uninspired for the most part with a couple of exceptions. You will have flashbacks to other past fights due to how similar they play out. I think From has just reached the limit on the combat system and boss design and at this point are just doing variations of the same types of fights over and over. It was almost a relief when I found an optional boss that played different even if the fight was nothing to write home about.
The are still issues with overly strong tracking, input reading and the like. To give an example on how bad it gets. After beating the final boss, I decided to watch some no-hit videos to see how they deal with certain attacks. One, of course, was Ongbank. And I was very amused when I saw one thing: in the second phase, when the boss has his back turned around and is recovering from one of its attack animations, Ongbank either did a single attack, or no attack at all despite having more than enough stamina and the boss was still recovering. The reason for this is that, if he did, the boss would have cancel its animation, start attacking and suddenly do a 180º turn, and if RNG decided to fuck you over and the attack he chose was a fast one, specially one that is pretty much impossible to dodge without a certain talisman, you are almost guaranteed to get hit. It is very poignant compared to Ongbanks other videos where he dances around the bosses attacks in creative ways, keeping always at the offensive, here he is forced to do the dance, hit, dance, hit add nauseum. This makes fights feel quite repetitive, specially when almost all bosses fights play similarly.
A new problem that is added to some of the bosses is a visual effect overload. The final boss is very guilty of this. It makes learning the fights an absolute pain in the ass and getting hit just because you were unlucky and a light effect blinded you for a second and made you misread an enemy attack really sucks. I swear, the Final boss second phase looked at times like a Data Fight from fucking Kingdom Hearts, I shit you not. Some bosses also have camera issues, I felt often times that the camera was way too close, specially for big enemies or those that love to jump. You expect after so many games that they would had fixed it or at least design the fights to take the camera into account, but they still don't. You can break the lock on, but certain weapons and Ashes of War really depend of you being locked on to work right (as it was the case with the one I was using).
Finally, as always, many of the fights are extremely built around rote memorization, much more than many other action games. Because of the nature of the character moveset, the only way you will find out the bosses' openings and how long you can exploit them, or what is a safe distance to outpace the enemy attack, is by being hit. Enemies will cancel their animations, slide around or read your inputs. Almost all enemies attack have delays or fake outs that you must learn either by getting hit or playing extremely passively, because even if you are able to react to them, the animation lock of your character will make sure you get hit if you try to attack. You cannot even play it smart and try to bait the feints by using a fast attack, because even with a small weapon your recovering is so long you will get hit. I wish the game had a feint system like For Honor, or even let you cancel an attack before the damage frames become active like God of War, wich allowed to feint the enemies. It feels like something that would be apropiate for Souls games
The thing with feints and delayed attacks reaches a point of parody in one instance. One of the bosses wiil jump up high in the air, hold its spear at ready, emit purple magic particles, stay in the air building expectation, and as you get ready to dodge as soon as he launches... he gets back to the ground and charges normally. First time it happened to me I actually chuckled because it felt like a self aware joke by From. Got hit the first time he used that attack, never again after that because ironically the overly long animations makes it easier to dodge. It was quite silly.
Funny enough, once you get acustomed to this issues, most of the boss pattern's are actually quite simplistic in nature, and the fights themselves are nothing to write home about, but the visibility issues does make some fights a chore to learn, as it takes even longer to decipher exactly what happened. Most second phases are just the first one but with an extra effect added to the enemy attacks, plus some new attacks. Once you realize this you only need to learn the new attacks and hope you do not get unlucky and the spectacles of lights throw you off mid fight.
Overall, if you liked the fights of the base game, you probably will like these, Mesmer in particular I think was actually fun. But I found myself a bit tired by the end.