Not that great
It took too much time to get to the boss, no pickups, and none of the stuff you would want to see from this kind of game. Also, The boss took way too long to kill, and it was a chore to get it done. There is no score system or powerups, so the only purpose of the basic enemies is to wear you down. As such, there is no need to kill anything except for the boss. Also, if you die you are transported back to the beginning of the level, which is just unforgivable, especially since you can spend the better part of 2 minutes wearing the boss down, and even more time getting back to that point. It needs a lot of changes.