The game isn't bad. Not exactly the best metroidvania, and the music doesn't match the game, at least in my opinion (I may be biased by the actual metroid and castlevania, as they have a much less relaxing ost), but I've played through worse games.
If I have to point something that really bothered me, is the hp. I'm going to guess that drinking the bottle from the sucubus in the very beggining gives you 300 hp instead of the standard 100 hp. Well, if you have to reload, for some reason, in the first stage, if you didn't drink the bottle, it reloads with 300 hp. After I finished the first stage, when I reloaded the first two times it gave me the hp I actually had (110 hp at that moment), then it reduced it to 100, and once I recovered all the skills, it went up to 320 (I got another expansion, so I should have 120).
Looks like a free buff, ain't it? The thing is, I wanted to play the game in the hard difficult, not the easy one. Both because I can smell a trap like that from several kms away (I'm gonna guess that drinking the bottle, and the game gives you two chances of doing so, makes it so it gives you the bad ending) and because I wanted the... challenge, if you can call ending this game with 120 or so hp challenging, as the worst part of said challenge is certain jumps where if you fuck up, the spines are going to kill you given enough time, as they stunlock you to death, so it doesn't matter if you have 100, 300 or 1 billion points of hp, except that it gives you the gameover screen faster so you have to endure the stunlock less time.
Besides that, the art is pretty, the animations aren't bad and besides the game deciding to stunlock you to death, it doesn't move as bad as I expected, with a bit of polishment (like making the dashing through enemies consistent, instead of not letting you pass through them if you are too close, or making it so it is a cancel move, like any half decent metroidvania with this mechanic does) I could go as far as to say that it actually has a good control. The first stage is also a good tutorial, giving you your full power and a brief explanation of what does every button, and let you experiment, so that you can get a feeling of how the character moves.