It's a great game.
As I played this, I was brought through a story of a man's life. It was invigorating and overwhelming to see this mans sad tale of life. At the end, I believe the game was about athiesm. Once you get both endings, you realize that.
The first ending was where you beat all the levels normally and the main character contemplates on whether he dies and travels to paradise, or just trades on nightmare for another. The next ending is where you get all of the yoshieggs, in each level and jump off the ledge, into darkness. This was a metaphor for how a man doesn't want a heaven, but simply wants rest and belation, so that he may pass on. The symbolism was very well done.