The free version fails to showcase the most important - the girl's growth and different paths of it. In the free 23 levels she grows about 10 cm, but visually that changes pretty much nothing. For example, her sprite won't change even if you put 6 magic power points at once (this is for BE). So the demo fails to demonstrate her change at all. You can only change her clothes and that's 3 sprites (it's cool that naked one was implemented, but it's strange how she and the hero have zero reaction about her being naked).
Battle is straightforward, but grindy and repetitive since the only way to get stronger is by leveling and you are being level balanced instantly, so it feels like there is no progression. Between two parties of hero lvl 20, demoness lvl 1 and hero lvl 40, demoness lvl 23 there are only 2 differences: stat and damage numbers and what the demoness says. Everything else stays the same.
I have no idea what's in the payed version, but the demo should show at least 1 sprite change, preferably with the mentioned different paths depending on upgraded stats.
In the end, the art is nice, development is active, but the demo needs plenty changes to be the real demo.
Don't you worry, I paid for the paid version and the only thing that happens is the sprite scaling bigger. Be, AE or WG paths all have no scaling for now. Also, if the sprite scales over a cenrtain size it disappears and it lags out your game a lot cause it still tries to apply physics to it. At least, it's laggy for my 3060.