TLDR: To be honest, it's kind of hard to say what this DLC does well that I like. Maybe I might just chalk it down to it's more content and it was apart of the season pass.
The Long:
I bought Season pass 1, out of the four DLC, Empires and Ashes is the only one, that I grudgingly gave a recommendation. For additional context, I only play single player, usually with maximum players and largest map distance. I do not pick what is the strongest, I pick and build characters based on roleplaying for said character.
To begin with, I must state, that before this DLC came out, the description for Primal Fury was something like explore the fae realms and unleash your inner beast. I was much more excited for the FAE part of that, which I am sorely disappointed with. I was expecting a new fairy transformation that, considering angel was already in the game, I figured it would just shrink your models and basically replace the angel wings with fairy wings. But, more on that, I find the culture to be the most important addition, so I start with that.
The Primal culture has a very tribal feeling where, roleplay wise, your people basically worship 1 of 7 animals that also has a terrain and terraforming capability tied to it usually. They are the Mire Crocodile of Swamp, Storm Crow of Grassland, Glacial Mammoth of Arctic, Ash Sabertooth of Ashlands, Dune Serpent and Desert, Tunneling Spider of the underground, and the Sylvan Wolf of the Forest. Part of your gameplay is to find shrines of your spirit and annex them to your empire. The Primal Culture starts off with a very good spell to summon their spirit animal in battle and it can be summoned anywhere. Why not plop down that sabertooth right behind your enemy's archers? Admittedly, (Disappointment from the fae part aside) I was not expecting to like Primal, but I like Primal. It doesn't feel lacking or limiting unlike some other culture choices and thus has room to roleplay thematically with various things.
I have frustration with the two forms added. With the addition of these two forms, there are now 7 beast races, and 6 humanoid races, with Goblin and Avian sitting on the sideline. Why is there no alternate idle and at least movement animations for the beast races? Why do the Lupine, the Tigrans, the rats, why do these races move exactly like the Humans, Elves, and Orcs? This is my biggest gripe with these forms. They should have come with alternate idle and at least movement. These forms lacking this, makes them lack the feel of the form and ultimately discourages me from wanting to actually use these forms. Primal Fury also adds in the ability for your race to have Elephant and Mammoth Mounts which is form trait, so I'll put it here; was great for me recreating the Great King of Nanzhong and the Worldwalkers of Norsca. The other two mounts don't require a trait and can just be selected in your race's appearance customization screen.
The Tome of the Stormborne: Bounty of the Sea: is a city spell that doubles base income from coastal provinces but lowers city stability for some reason, instead of like lowering income from land provinces. Stormport is a stackable building, that gives more mana and gold for each one built in your empire. The Stormbringer is a T4 skirmisher that hits in a line, but it's melee attack also deals some lightning damage to two other enemies within two hexes. Downpour is a world spell that turns the province into swamp, and makes it downpour for 3 turns. Any units in combat in downpour become wet and slowed, but amphibious and water movement units are immune. Lastly is the major transformation Naga, which gives amphibious, fast movement, the great passive of slip away (that enables units to survive a fatal hit, teleport away 3 hexes and heal 15HP), gives blight and lightning resistance, and becomes immune to electricity. I guess you're more of an electric eel or something, because lightning resistance and immune to electricity doesn't make much sense to me. That said, if we can be honest, Naga transformation doesn't look that great because well, they just fade out the legs and put the very stiff tail under it. Just imagine, if they did those alternate beast animations, it would look much better on Naga than the standard use Human rig.
Lastly is the Tome of the Fey Mists. No Fairies, no fairy wings, but personal gripes aside, you have summon Mistling. A T3 skirmisher that looks like a gremlin and not like a fairy, that despite my gripes, is actually very good. It's melee attack will teleport it away, enabling to get back to range if it was locked down, and it's range attack has a 90% chance of inflicting a random debuff on the enemy. The Feytouched minor race transformation, that gives your race the buff of removing a debuff when entering mist or obscured; as well as ignoring aim penalties from enemies being in mist/obscured themselves. Fey Embrace is a combat spell that places Mist in a 1hex aoe, and also gives 2 buffs. Staves of Mist enchants your supports, giving them a free use ability that heals 10HP, gives clinging mist (reduce enemy chance to hit by 15% that can stack 3x btw), and also gives a random buff. Lingering Mists is a world spell that makes the province misty for 3 turns, which lowers vision range, gives universal camoflauge, and makes mist appear in battle. Lastly, although I usually kind of ignore the special province improvements, I have to talk about Feywater Pond because it has a flaw IMO. So when you build the Feywater Pond in your city, that entire's city domain becomes enshrouded in mist. Remember, this means universal camoflauge, which means, your enemies can't see you... but you also can't see them. Why is an enemy able to hide in my domain when I'm the one with with Fey buff and I can't see them? Why doesn't the Feywater Pond additionally give true sight or Fey sight or something of this sort so that they can see enemies in their own domain? It is so bafflingly designed that I do not understand how this benefits anything that's not the AI. After I learned that I can't see enemies, despite having Feytouched, I never built the Feywater Pond outside the capital again, and that's because the capital has a building that gives true sight from the wizard's tower.
There's not even a building that allows you to build fairies, which are actual units in the base game. Like I said, I got bamboozled hard by the initial description of Primal Fury; but I still recommend this DLC, issues aside. If they ever make an alternate set of more bestial locomotion I'd be happy, especially since half the forms at this point would benefit from it.