I'm going to focus on comparing that one to Horizon Gate.
From a pure gameplay perspective, I much prefer HG. Kingsvein has a lot less character building options - less classes, less weapons, less weapon types, less armor tiers, just less everything. While I understand this is in service of a more focused gameplay experience, I have to admit the handful of classes in Kingvein don't quite put me in a build-making frenzy like HG does, and I can't help but be a bit disappointed. But again, this was done for a good reason and I can accept that.
What I have more trouble accepting is another change to the gameplay - namely, the change from a time units based combat structure to a I-go-you-go based one. In HG, combat progressed according to a timeline - units got their turn when enough time units had passed for their "wait" bar to fill (and there were a handful of ways to manipulate that), and delayed abilities also worked with those time units, with stronger abilities taking longer to cast, and therefore increasing the odds that enemies would have time to act before the ability went off. Status effects also worked with this system, with a duration in time units.
This is all gone in Kingsvein. Instead, in each combat, all the units on your side go first, in any order you wish, then all enemies go. Rinse and repeat. There is no concept of "time units" anymore, only "turns" - with a turn being defined as both sides having acted. To accomodate that, delayed abilities - all of them -now go off after a turn has elapsed. Meaning, regardless of what you do, all enemies will have time to act before your ability goes off.
This has two main consequences. The first is that it's now trivially easy to coordinate two or more characters with complementary abilities. Have one character apply a bunch of debuffs, then a second cast shatter - congrats, you've just one shot an enemy, and you can do that every turn without fail.
The second is that about a third to a half of all abilities are now more or less worthless, because they're delayed abilities, and delayed abilities [i]will not land[/i] in this game. Oh sure you can do a complicated multi character setup to ensure your target can't escape before the ability goes off, but since there are no hard CC in this game this'll take quite a bit of effort and coordination - with which you could simply use instant cast abilities and kill the target before its turn even comes.
Well, that's not entirely true. Delayed abilities aren't entirely useless - because the AI seems [i]terrified[/i] of them. "Getting out of delayed abilities' AoE" (and "not getting in AoE") apparently is a huge priority in the AI logic, even for abilities that aren't all that strong, and as a result you can use them as general area denial instead of their normal effect. I've won a couple of hard fights rather easily by just preparing a Quake (biggest AoE in the game) and hanging back - each time one strong enemy would brave the AoE to hit my caster, while the rest of their team would cower far away, allowing me to divide and conquer and focus on the main threat safely.
I'm fine with changes to the overall amount of classes and equipment if it serves the game's context, but this new turn structure is, in my opinion, a strict downgrade from the previous system, and I really hope it doesn't stay around for the next game.
Now onto more positive stuff : the story. In this area, Kingsvein is much better than HG. HG had honestly just a vague excuse of a story, a simple justification as to why you've got a boat and are running around. Kingsvein, while not a narrative heavy game by any mean, is much better in that regard. Instead of a big overworld peppered with mini dungeon here and there, here you run around several interconnected areas, which helps a lot with keeping a cohesive story, keeping NPCs relevant, etc.
Still, story isn't necessarily one those games' strong points... But worldbuilding is! Like all previous games, you can examine pretty much everything you come accross. And since Kingsvein takes place in a different realm than all other games, there's a lot of new stuff to find out. Having played this, I feel like I'm starting to get how this game world works a bit. That's a good feeling.
So overall, yes, it's a great game. Worth playing, well made, and I recommend it heartily. I just don't see myself putting in as much time in it as I did (and will continue to do) in Horizon's Gate.
