Well, I finished the demo. Overall, I'm honestly pretty happy with it. Sure, the battle animations are bad (better than Re:Incarnation though) and I'm iffy about some of the music remixes but otherwise? It looks great to me.
After playing with it, I feel the new art is pretty good actually? It took me a bit to warm up to it but I really like it now, the new Cherie in particular.
Anyway, more importantly: gameplay. It certainly plays like Langrisser, but there's some pretty significant differences compared to the original. Is the high CP gain demo-specific? Characters seems to be going through the promotion tree really quickly: my Cherie was already third tier. But yeah, 30CP to get third tier with 5CP gained per level means that you get it after 6 additional levels (instead of 10), with the second tier even faster. Your level also keeps going up instead of reseting to 1, but that makes sense with the "freeform" class changing.
The 10HP system is gone, replaced with higher values and higher stats values on the whole. I feel the new system works a bit better than the original, since it helps prevent the "invincible unit" syndrome, since you still take some damage even from units with lower attacks than your defense. It's a bit harder to estimate the damage beforehand, but you have a battle forecast window now so at least on the offense you have good information.
Dex and Agi? What do those do..?
No self-healing means enemy commanders are more suicidal than before. It makes it both easier and harder since they are now harder to manipulate (before, 7HP = they rest even if they could defeat an unit).
This is the best implementation of the "automated troop movement" that I recall. Every single time I used it, the mercenary units all formed correctly around my commanders even at max movement; I recall in other games often finding myself with the furthest merc going to the back, and thus have none able to go in front. I'm pretty happy to see it since trustable movement AI means less need to manually move all of them when out of combat.
I feel the unit matchups is less significant now? They obviously still affect combat, but things like pikeman vs cavalry or monk vs slime doesn't feel as one-sided as before.
The biggest "nerf" I see is the lack of attack priority: before, units attacked at different speed and it was possible for some units to take out some enemies before they even attacked. It does equalize classes more since it means units like Lester's sea serpent won't be disadvantaged anymore, but I feel it does rob some uniqueness away.
Overall, I feel the "flow" and timing of the stages worked well even with all the changes. I feel things were happening at the right time, allied units were beaten at the appropriate time based on where I was and things were tight without being overwhelming. I can't say it necessarily feels "better" than the original, but it's both different and similar.
It's pretty enjoyable, and it's a day 1 preorder for me if it comes out in English. If it only comes out in Japanese I'm not sure though; I did play Der Langrisser in Japanese, but I mostly stumbled my way through it. I don't have as much time as I did back then to translate bits and pieces, and there's way more SRPGs available now.