Really loving the game so far, it's definitely got that "one more round" pull to it.
One thing I noticed was that for quite a while I didn't understand how losing health when you fall through a hole worked. Because your heart meter is hidden while you're falling down, it didn't occur to me that I could lose more than 1 heart while falling--the red indicators didn't fully signal to me what was going on. Even now that I understand that, it always feels like a surprise whether or not I'm going to die when I fall through a hole.