This has potential to be way better, but it is pretty solid as it stands. My main issues (besides the price) are: enemy tanks clearly pop in, track physics/animations are rough, graphics are nothing amazing. I come from War Thunder, and have never played WoT and I'd say this is pretty solid. But the price is really high, at least for now, try to buy on sale.
This demo is entertaining, and I'm excited to pick up the full game. I won't get into the specifics of the story, but it's a novel idea. The dialogue wasn't too long either, which is usually why I can't get into visual novels. I saw another reviewer talk about the gameplay being boring, but it really wasn't for me. And, no, you don't have to use Kurokami's arm for every fight. Whether the person didn't experiment or not I have no idea, but it is possible to defeat enemies without her arm. You really have to plan your attacks and order of method carefully, or you won't finish the demo. Another thing to note, usually I don't like when games put artificial pressure on the player via a time limit or a move limit but this game does it well. And it doesn't feel like I'm under a lot of stress. I'm excited to try out the full game.