I finished it today. It's really something overall. A little overwhelming. I wish it provided more direction sometimes as to where to go and what to do. I had to turn to the help thread more often than I like. An overworld map would have been awesome. Don't worry, if you beat Level 16 you can still do the rest.
It's really easy once you get the most powerful items. The only things I didn't get were a smattering of heart container pieces.
Edit: The other thing is it gets a little easier once you figure out how the levels work (i.e., four worlds, each divided into four quadrants, 1 numbered dungeon in each). Until you figure that out though, it's really easy to feel adrift in a vast world.
Edited by SofaKing, 15 August 2015 - 08:00 PM.