While there are quite a few great aspects to this DLC, it's held back by two major flaws: Fromsoft apparently straying away from the base design and philosophy, and ignoring their limitations.

With so many game mechanics, animations and weapons taken from previous games, sometimes with no modification, it is quite important for new additions to be designed to be coherent with the old assets a huge part of the game is based on.

With most weapons retaining the relatively slow and awkward moveset we found in previous Dark Souls games, that look like what someone who never used a sword would do (barring a couple exceptions), it seems important for most new weapons to keep that feeling. Yet From adds more and more weapons that give the user very skilled and graceful movement.

The same character will awkwardly swing around a war axe, then expertly dance around with a bastard sword and precisely strike his opponent, for example.

Over-the-top attacks always existed, like the demon greataxe's weapon art, but we didn't have too many of them, and they generally didn't go too far. Now we have a huge selection of attacks that spawn giant AoE effects, or make you literally fly for a few seconds and over several meters, or spawn a billion particle effects.

The issue is not that these kind of things exist, since they kind of always did, it's that they now go VERY far and are getting too common.
The issue is that we have a huge part of the game that seems designed like an extension of previous Dark Souls titles, but mixed with another solid chunk that seems designed for a very different game. The contrast is noticeable and quite jarring.

In the same vein, and overlapping with the second flaw, is the new boss designs. More and more of them will spawn huge AoE attacks, sometimes with lingering hitboxes, move very often and very far in the arena, have attacks with very fast start-up and short cooldowns, and very long combos. With a movement system that is so similar to Dark Souls 3, where everything is much slower and deliberate, it just doesn't work.
We now have to spend good portions of many boss fights running away from attacks, running towards the boss that flew on the other side of the arena, having little to no time to either recover or attack after a long-winded combo. It feels less like a fight, and more like getting bullied, holding our breath in wait for the boss to let us hit him.

The second flaw comes with From's limitations. They've never been the best when it comes with optimization, camera work, and comfortable movements.

Yet they put many bosses that jump around A LOT, which just doesn't work with a bad camera.
Then the exact same boss will spawn a billion particle effects, which will completely tank your frame rate, and often block your vision of the boss.
If both happen at the same time, you just have absolutely no idea what is happening. It is a confusing jumbled mess.

A few bosses even have to be fought on very uneven terrain. Your opponent is jumping around, pushing you God knows where with his very oppresive attacks and with the fairly unhelpful camera, and you're suddenly stuck on some random lip in the ground or in a tree, blocking either your attack or escape route.
Even worse, you stagger the boss, only for his weak point to sink in the terrain or be lifted way out of reach.
Rivetting gameplay.

Absolutely all of this culminates in the last boss of this DLC, which is maybe the worst of the entire game:
Uncharacteristic design and attacks that look like they're from another game, extremely oppressive attacks, bad camera, screen is filled with a jumbled mess that tanks your frame rate, and you even have a slightly uneven terrain (luckily, it didn't seem to matter here).

All of this was already in the base game, but my problem is that they doubled down with them in the DLC.
From made big mistakes with DS2 before creating three masterpieces in a row, so I keep hope they will realize the ones they did in Elden Ring and do better in the future.

But we now have Igon, which is great.
Curse you, Bayle.