The visuals and audio are top notch. The game plays at a great frame rate and, up to a point, it's challenging but fair. Learning that you can die as much as you like makes it much easier to put up with the challenge. The game is very hard at the start since you don't have projectiles, but it's very doable with a few deaths. The scythe boss is very annoying and not fun to play against.
The trouble is the final boss. I've finally had to give up on seeing the ending. The final boss isn't worth any more of my time. It's really a shame, since I wanted to know where the interesting story was going. I was really down with the mood this game was putting out. Sadly, the final boss marks a point where the developer forgot the whole "firm but fair" thing. What kept me going throughout the game was that it was difficult but did seem to want to avoid turning into a masochist simulator. The final boss is a masochist simulator. There's no real way to beat it without getting lucky. There's no special trick or challenge which, once surmounted, will let you defeat it. You just have to pray. It's the hardest enemy in the game by far, and you fight it after slowly losing max HP throughout the course of the game. Why? Why do you fight the hardest enemy with the least HP? It should be the opposite.
The final boss and the scythe boss both share a common quality: They fill the screen with enemies too quickly for you to kill them. The snake boss does this, too. You could deal with the scythe and snake bosses by rushing them down and hoping for the best. You can't do that with the final boss. You can't rush him down and kill him quickly, and you can't keep him from filling the screen with enemies. 3 reasons why: The scythe enemies are too difficult to kill before they dive, the snake enemies spawn more of themselves, and the boss spawns minions too quickly. I would recommend cutting the boss's attack speed in half. That would make it challenging but entirely possible to keep the spawned enemies off the screen.
Ultimately, a pleasant experience cut short by an awful boss. Wish I could see where the plot was going, but 99% of players won't. Most of them didn't even make it past the first dungeon.