Hey Rommel, I had the chance to play a little bit of your game. I didn't manage to complete the demo but I managed to reach the second area.
My first suggestion would be to provide the player with a checkpoint or a save point there (at the start of the caves), I didn't want to go through the beginning again, since it mostly felt like an introduction like in Symphony Of The Night.
I felt the attack to be often unresponsive and the sword animation to be in serious need of a follow-through. Right now it feels a little bit odd that the animation finishes mid-way.
I really enjoyed the music you chose for the opening sequence and the sound effects for the menus are very nice and juicy. However, the sound the enemies make when they get defeated overpowers any other sound in the game, so I would suggest turning it down. Some of the pixel art in the houses looks really well done, but some of it on the environments I feel doesn't have the same level of care and polish, so it feels odd to jump between quality so often.
Keep working at it, I really like metroid-vanias, and I would be down to test it again and give you my thoughts once you do some tweaks. ;)