I like the game, It feels pretty good to play, but I just have a few bits of advice.
I would work on the movement in the overworld, it just feels a little stiff. Maybe make it slightly faster. The title screen seems to be a little messed up, not sure if its on newgrounds end or yours. Some of the text goes of screen or clips through other bits of text, still not sure if that is newgrounds fault or not. The audio is a little unbalanced, and is especially noticable with the jump noise. Those are my only big issues with the game, so now I can move onto the great things about the game. For one, the art is fantastic, really good original sprite work, so serious praise there. The music is pretty good as well, especially the house music. I also like how smooth the scrolling is on the 2D sections, it looks really good.
Overall, I would say this is a pretty good first attempt, you just need to polish it a bit. Good luck on your next project, because I can't wait to see what you make!