Here are my first impressions and also final impressions until the game is further into development.
TL;DR: If you're looking for Battle Brothers in 3D, prepare to be disappointed. Otherwise, it's promising.
Overall Wartales seems like a decent 3D RPG in the same vein as Battle Brothers (or a turn-based Mount and Blade), although I'm hard-pressed to list anything it does better than BB, outside of the 3d preference.
Technical
Firstly, the game is very light on graphical settings, but that can be semi-forgiven as it is in Early Access. Resolution seems locked to 1920x1080, and there's no option for text size, which is absurdly small (or maybe I'm just old). The zoom is horrendous. Using the mouse wheel to zoom in only does so by the barest amount (why even bother?), so expect to squint at your characters both on the campaign map and battle maps.
The game itself seems to run fine, save for some microfreezing when loading into a battle.
Character creation
There is no character creation, outside of choosing what starting group of mercenaries you have, and what bonuses are applied.
Party management/Classes
Seems pretty robust if somewhat standard. Companions are separated into classes, depending on what weapon they wield (haven't played enough of the game to do a deep dive into class balance). You can rest via a campfire, which is also when you feed and pay your mercs (which isn't automatic, you have to do this manually). Unfortunately, companions have no real relationship mechanics or anything to set them apart from being meatbags for combat.
Items also locked to classes, or non-combat "professions" that your mercs can get. Very little character customization at all outside of equipment.
Combat
Ooooof. Here is where the gripes come in. Keep in mind that I love Battle Brothers and I develop systems similar to BB (in a weird hybrid dnd 5e + FF tactics way).
Combat is distressingly gamey, as opposed to simulationist. The set up phase is barely there. You get a small number of arbitrary spots where your companions can load in, and that's it. Put all your melee in the front, ranged in the back, and that's all the flexibility you get, regardless of how you meet/ambush the enemy.
The turn order is also different. Wartales uses an Open Turn Order, where you can choose any unit that hasn't taken their turn yet. I don't like this system because it's just... too easy.
Engaging an enemy in close quarters "locks" you into melee combat, sort of like DnD. However, "disengaging" will trigger an opportunity attack. This is bound to be confusing for some based on the wording.
A lot of weapons are AOE, and they also do friendly fire. You can normally aim the attack cone, except when you're locked in melee combat, then the cone is fixed. There is NO option for non-AOE attacks with weapons such as two handed swords or axes (lol wut?).
Spears and polearms push enemies back with the "impale" attack (lol wut? x2).
So just with these basics, you can see how a typical combat encounter could be gamey and cheesed, rather than somewhat simulationist/realistic like BB.
Combat overall is extremely easy to anybody with experience in these types of games. Enemy AI is sufficient, but I haven't seen anything too spectacular or challenging. Most early games mobs are just the standard bandits.
Action economy is also similar to DnD. You get movement, one attack action, and some bonuses. Some of the "bonus actions" for the lack of a better word, are very strong and this is balanced by [resource name that I forgot].
Crafting
Lol, I didn't do any of this. Or the minigames, as they seemed tedious.
Campaign
Similar to BB. You can go to towns (which have buildings with interiors) to pick up missions and talk to NPCs, etc. After picking up a mission, your map is marked. Random mobs and be interacted with (usually just attack, steal or leave). Doesn't seem to have much in the way of faction systems at this point, outside of Reputation.
There does seem to be more depth in some areas, but I haven't played enough to find out.
Wartales in it's current state is the definition of what's wrong with Recommended/Not Recommended review systems. It's a 6/10, but according to Steam, it's 87% positive. Tbf, the devs did put their work in and it's very promising. While it doesn't rival Battle Brothers at it's current stage, it may one day.